package fzf

import (
	"fmt"
	"os"
	"regexp"
	"strconv"
	"strings"
	"unicode/utf8"

	"github.com/junegunn/fzf/src/algo"
	"github.com/junegunn/fzf/src/tui"
	"github.com/junegunn/fzf/src/util"

	"github.com/junegunn/go-shellwords"
)

const usage = `usage: fzf [options]

  Search
    -x, --extended        Extended-search mode
                          (enabled by default; +x or --no-extended to disable)
    -e, --exact           Enable Exact-match
    --algo=TYPE           Fuzzy matching algorithm: [v1|v2] (default: v2)
    -i                    Case-insensitive match (default: smart-case match)
    +i                    Case-sensitive match
    --literal             Do not normalize latin script letters before matching
    -n, --nth=N[,..]      Comma-separated list of field index expressions
                          for limiting search scope. Each can be a non-zero
                          integer or a range expression ([BEGIN]..[END]).
    --with-nth=N[,..]     Transform the presentation of each line using
                          field index expressions
    -d, --delimiter=STR   Field delimiter regex (default: AWK-style)
    +s, --no-sort         Do not sort the result
    --tac                 Reverse the order of the input
    --tiebreak=CRI[,..]   Comma-separated list of sort criteria to apply
                          when the scores are tied [length|begin|end|index]
                          (default: length)

  Interface
    -m, --multi           Enable multi-select with tab/shift-tab
    --no-mouse            Disable mouse
    --bind=KEYBINDS       Custom key bindings. Refer to the man page.
    --cycle               Enable cyclic scroll
    --no-hscroll          Disable horizontal scroll
    --hscroll-off=COL     Number of screen columns to keep to the right of the
                          highlighted substring (default: 10)
    --filepath-word       Make word-wise movements respect path separators
    --jump-labels=CHARS   Label characters for jump and jump-accept

  Layout
    --height=HEIGHT[%]    Display fzf window below the cursor with the given
                          height instead of using fullscreen
    --min-height=HEIGHT   Minimum height when --height is given in percent
                          (default: 10)
    --reverse             Reverse orientation
    --border              Draw border above and below the finder
    --margin=MARGIN       Screen margin (TRBL / TB,RL / T,RL,B / T,R,B,L)
    --inline-info         Display finder info inline with the query
    --prompt=STR          Input prompt (default: '> ')
    --header=STR          String to print as header
    --header-lines=N      The first N lines of the input are treated as header

  Display
    --ansi                Enable processing of ANSI color codes
    --tabstop=SPACES      Number of spaces for a tab character (default: 8)
    --color=COLSPEC       Base scheme (dark|light|16|bw) and/or custom colors
    --no-bold             Do not use bold text

  History
    --history=FILE        History file
    --history-size=N      Maximum number of history entries (default: 1000)

  Preview
    --preview=COMMAND     Command to preview highlighted line ({})
    --preview-window=OPT  Preview window layout (default: right:50%)
                          [up|down|left|right][:SIZE[%]][:wrap][:hidden]

  Scripting
    -q, --query=STR       Start the finder with the given query
    -1, --select-1        Automatically select the only match
    -0, --exit-0          Exit immediately when there's no match
    -f, --filter=STR      Filter mode. Do not start interactive finder.
    --print-query         Print query as the first line
    --expect=KEYS         Comma-separated list of keys to complete fzf
    --read0               Read input delimited by ASCII NUL characters
    --print0              Print output delimited by ASCII NUL characters
    --sync                Synchronous search for multi-staged filtering

  Environment variables
    FZF_DEFAULT_COMMAND   Default command to use when input is tty
    FZF_DEFAULT_OPTS      Default options (e.g. '--reverse --inline-info')

`

// Case denotes case-sensitivity of search
type Case int

// Case-sensitivities
const (
	CaseSmart Case = iota
	CaseIgnore
	CaseRespect
)

// Sort criteria
type criterion int

const (
	byScore criterion = iota
	byLength
	byBegin
	byEnd
)

type sizeSpec struct {
	size    float64
	percent bool
}

func defaultMargin() [4]sizeSpec {
	return [4]sizeSpec{}
}

type windowPosition int

const (
	posUp windowPosition = iota
	posDown
	posLeft
	posRight
)

type previewOpts struct {
	command  string
	position windowPosition
	size     sizeSpec
	hidden   bool
	wrap     bool
}

// Options stores the values of command-line options
type Options struct {
	Fuzzy       bool
	FuzzyAlgo   algo.Algo
	Extended    bool
	Case        Case
	Normalize   bool
	Nth         []Range
	WithNth     []Range
	Delimiter   Delimiter
	Sort        int
	Tac         bool
	Criteria    []criterion
	Multi       bool
	Ansi        bool
	Mouse       bool
	Theme       *tui.ColorTheme
	Black       bool
	Bold        bool
	Height      sizeSpec
	MinHeight   int
	Reverse     bool
	Cycle       bool
	Hscroll     bool
	HscrollOff  int
	FileWord    bool
	InlineInfo  bool
	JumpLabels  string
	Prompt      string
	Query       string
	Select1     bool
	Exit0       bool
	Filter      *string
	ToggleSort  bool
	Expect      map[int]string
	Keymap      map[int][]action
	Preview     previewOpts
	PrintQuery  bool
	ReadZero    bool
	Printer     func(string)
	Sync        bool
	History     *History
	Header      []string
	HeaderLines int
	Margin      [4]sizeSpec
	Bordered    bool
	Tabstop     int
	Version     bool
}

func defaultOptions() *Options {
	return &Options{
		Fuzzy:       true,
		FuzzyAlgo:   algo.FuzzyMatchV2,
		Extended:    true,
		Case:        CaseSmart,
		Normalize:   true,
		Nth:         make([]Range, 0),
		WithNth:     make([]Range, 0),
		Delimiter:   Delimiter{},
		Sort:        1000,
		Tac:         false,
		Criteria:    []criterion{byScore, byLength},
		Multi:       false,
		Ansi:        false,
		Mouse:       true,
		Theme:       tui.EmptyTheme(),
		Black:       false,
		Bold:        true,
		MinHeight:   10,
		Reverse:     false,
		Cycle:       false,
		Hscroll:     true,
		HscrollOff:  10,
		FileWord:    false,
		InlineInfo:  false,
		JumpLabels:  defaultJumpLabels,
		Prompt:      "> ",
		Query:       "",
		Select1:     false,
		Exit0:       false,
		Filter:      nil,
		ToggleSort:  false,
		Expect:      make(map[int]string),
		Keymap:      make(map[int][]action),
		Preview:     previewOpts{"", posRight, sizeSpec{50, true}, false, false},
		PrintQuery:  false,
		ReadZero:    false,
		Printer:     func(str string) { fmt.Println(str) },
		Sync:        false,
		History:     nil,
		Header:      make([]string, 0),
		HeaderLines: 0,
		Margin:      defaultMargin(),
		Tabstop:     8,
		Version:     false}
}

func help(code int) {
	os.Stderr.WriteString(usage)
	os.Exit(code)
}

func errorExit(msg string) {
	os.Stderr.WriteString(msg + "\n")
	os.Exit(exitError)
}

func optString(arg string, prefixes ...string) (bool, string) {
	for _, prefix := range prefixes {
		if strings.HasPrefix(arg, prefix) {
			return true, arg[len(prefix):]
		}
	}
	return false, ""
}

func nextString(args []string, i *int, message string) string {
	if len(args) > *i+1 {
		*i++
	} else {
		errorExit(message)
	}
	return args[*i]
}

func optionalNextString(args []string, i *int) string {
	if len(args) > *i+1 && !strings.HasPrefix(args[*i+1], "-") {
		*i++
		return args[*i]
	}
	return ""
}

func atoi(str string) int {
	num, err := strconv.Atoi(str)
	if err != nil {
		errorExit("not a valid integer: " + str)
	}
	return num
}

func atof(str string) float64 {
	num, err := strconv.ParseFloat(str, 64)
	if err != nil {
		errorExit("not a valid number: " + str)
	}
	return num
}

func nextInt(args []string, i *int, message string) int {
	if len(args) > *i+1 {
		*i++
	} else {
		errorExit(message)
	}
	return atoi(args[*i])
}

func optionalNumeric(args []string, i *int) int {
	if len(args) > *i+1 {
		if strings.IndexAny(args[*i+1], "0123456789") == 0 {
			*i++
		}
	}
	return 1 // Don't care
}

func splitNth(str string) []Range {
	if match, _ := regexp.MatchString("^[0-9,-.]+$", str); !match {
		errorExit("invalid format: " + str)
	}

	tokens := strings.Split(str, ",")
	ranges := make([]Range, len(tokens))
	for idx, s := range tokens {
		r, ok := ParseRange(&s)
		if !ok {
			errorExit("invalid format: " + str)
		}
		ranges[idx] = r
	}
	return ranges
}

func delimiterRegexp(str string) Delimiter {
	// Special handling of \t
	str = strings.Replace(str, "\\t", "\t", -1)

	// 1. Pattern does not contain any special character
	if regexp.QuoteMeta(str) == str {
		return Delimiter{str: &str}
	}

	rx, e := regexp.Compile(str)
	// 2. Pattern is not a valid regular expression
	if e != nil {
		return Delimiter{str: &str}
	}

	// 3. Pattern as regular expression. Slow.
	return Delimiter{regex: rx}
}

func isAlphabet(char uint8) bool {
	return char >= 'a' && char <= 'z'
}

func isNumeric(char uint8) bool {
	return char >= '0' && char <= '9'
}

func parseAlgo(str string) algo.Algo {
	switch str {
	case "v1":
		return algo.FuzzyMatchV1
	case "v2":
		return algo.FuzzyMatchV2
	default:
		errorExit("invalid algorithm (expected: v1 or v2)")
	}
	return algo.FuzzyMatchV2
}

func parseKeyChords(str string, message string) map[int]string {
	if len(str) == 0 {
		errorExit(message)
	}

	tokens := strings.Split(str, ",")
	if str == "," || strings.HasPrefix(str, ",,") || strings.HasSuffix(str, ",,") || strings.Index(str, ",,,") >= 0 {
		tokens = append(tokens, ",")
	}

	chords := make(map[int]string)
	for _, key := range tokens {
		if len(key) == 0 {
			continue // ignore
		}
		lkey := strings.ToLower(key)
		chord := 0
		switch lkey {
		case "up":
			chord = tui.Up
		case "down":
			chord = tui.Down
		case "left":
			chord = tui.Left
		case "right":
			chord = tui.Right
		case "enter", "return":
			chord = tui.CtrlM
		case "space":
			chord = tui.AltZ + int(' ')
		case "bspace", "bs":
			chord = tui.BSpace
		case "ctrl-space":
			chord = tui.CtrlSpace
		case "alt-enter", "alt-return":
			chord = tui.AltEnter
		case "alt-space":
			chord = tui.AltSpace
		case "alt-/":
			chord = tui.AltSlash
		case "alt-bs", "alt-bspace":
			chord = tui.AltBS
		case "tab":
			chord = tui.Tab
		case "btab", "shift-tab":
			chord = tui.BTab
		case "esc":
			chord = tui.ESC
		case "del":
			chord = tui.Del
		case "home":
			chord = tui.Home
		case "end":
			chord = tui.End
		case "pgup", "page-up":
			chord = tui.PgUp
		case "pgdn", "page-down":
			chord = tui.PgDn
		case "shift-left":
			chord = tui.SLeft
		case "shift-right":
			chord = tui.SRight
		case "double-click":
			chord = tui.DoubleClick
		case "f10":
			chord = tui.F10
		case "f11":
			chord = tui.F11
		case "f12":
			chord = tui.F12
		default:
			if len(key) == 6 && strings.HasPrefix(lkey, "ctrl-") && isAlphabet(lkey[5]) {
				chord = tui.CtrlA + int(lkey[5]) - 'a'
			} else if len(key) == 5 && strings.HasPrefix(lkey, "alt-") && isAlphabet(lkey[4]) {
				chord = tui.AltA + int(lkey[4]) - 'a'
			} else if len(key) == 5 && strings.HasPrefix(lkey, "alt-") && isNumeric(lkey[4]) {
				chord = tui.Alt0 + int(lkey[4]) - '0'
			} else if len(key) == 2 && strings.HasPrefix(lkey, "f") && key[1] >= '1' && key[1] <= '9' {
				chord = tui.F1 + int(key[1]) - '1'
			} else if utf8.RuneCountInString(key) == 1 {
				chord = tui.AltZ + int([]rune(key)[0])
			} else {
				errorExit("unsupported key: " + key)
			}
		}
		if chord > 0 {
			chords[chord] = key
		}
	}
	return chords
}

func parseTiebreak(str string) []criterion {
	criteria := []criterion{byScore}
	hasIndex := false
	hasLength := false
	hasBegin := false
	hasEnd := false
	check := func(notExpected *bool, name string) {
		if *notExpected {
			errorExit("duplicate sort criteria: " + name)
		}
		if hasIndex {
			errorExit("index should be the last criterion")
		}
		*notExpected = true
	}
	for _, str := range strings.Split(strings.ToLower(str), ",") {
		switch str {
		case "index":
			check(&hasIndex, "index")
		case "length":
			check(&hasLength, "length")
			criteria = append(criteria, byLength)
		case "begin":
			check(&hasBegin, "begin")
			criteria = append(criteria, byBegin)
		case "end":
			check(&hasEnd, "end")
			criteria = append(criteria, byEnd)
		default:
			errorExit("invalid sort criterion: " + str)
		}
	}
	return criteria
}

func dupeTheme(theme *tui.ColorTheme) *tui.ColorTheme {
	if theme != nil {
		dupe := *theme
		return &dupe
	}
	return nil
}

func parseTheme(defaultTheme *tui.ColorTheme, str string) *tui.ColorTheme {
	theme := dupeTheme(defaultTheme)
	rrggbb := regexp.MustCompile("^#[0-9a-fA-F]{6}$")
	for _, str := range strings.Split(strings.ToLower(str), ",") {
		switch str {
		case "dark":
			theme = dupeTheme(tui.Dark256)
		case "light":
			theme = dupeTheme(tui.Light256)
		case "16":
			theme = dupeTheme(tui.Default16)
		case "bw", "no":
			theme = nil
		default:
			fail := func() {
				errorExit("invalid color specification: " + str)
			}
			// Color is disabled
			if theme == nil {
				continue
			}

			pair := strings.Split(str, ":")
			if len(pair) != 2 {
				fail()
			}

			var ansi tui.Color
			if rrggbb.MatchString(pair[1]) {
				ansi = tui.HexToColor(pair[1])
			} else {
				ansi32, err := strconv.Atoi(pair[1])
				if err != nil || ansi32 < -1 || ansi32 > 255 {
					fail()
				}
				ansi = tui.Color(ansi32)
			}
			switch pair[0] {
			case "fg":
				theme.Fg = ansi
			case "bg":
				theme.Bg = ansi
			case "fg+":
				theme.Current = ansi
			case "bg+":
				theme.DarkBg = ansi
			case "hl":
				theme.Match = ansi
			case "hl+":
				theme.CurrentMatch = ansi
			case "border":
				theme.Border = ansi
			case "prompt":
				theme.Prompt = ansi
			case "spinner":
				theme.Spinner = ansi
			case "info":
				theme.Info = ansi
			case "pointer":
				theme.Cursor = ansi
			case "marker":
				theme.Selected = ansi
			case "header":
				theme.Header = ansi
			default:
				fail()
			}
		}
	}
	return theme
}

var executeRegexp *regexp.Regexp

func firstKey(keymap map[int]string) int {
	for k := range keymap {
		return k
	}
	return 0
}

const (
	escapedColon = 0
	escapedComma = 1
	escapedPlus  = 2
)

func init() {
	// Backreferences are not supported.
	// "~!@#$%^&*;/|".each_char.map { |c| Regexp.escape(c) }.map { |c| "#{c}[^#{c}]*#{c}" }.join('|')
	executeRegexp = regexp.MustCompile(
		"(?si):(execute(?:-multi|-silent)?):.+|:(execute(?:-multi|-silent)?)(\\([^)]*\\)|\\[[^\\]]*\\]|~[^~]*~|![^!]*!|@[^@]*@|\\#[^\\#]*\\#|\\$[^\\$]*\\$|%[^%]*%|\\^[^\\^]*\\^|&[^&]*&|\\*[^\\*]*\\*|;[^;]*;|/[^/]*/|\\|[^\\|]*\\|)")
}

func parseKeymap(keymap map[int][]action, str string) {
	masked := executeRegexp.ReplaceAllStringFunc(str, func(src string) string {
		prefix := ":execute"
		if src[len(prefix)] == '-' {
			c := src[len(prefix)+1]
			if c == 's' || c == 'S' {
				prefix += "-silent"
			} else {
				prefix += "-multi"
			}
		}
		return prefix + "(" + strings.Repeat(" ", len(src)-len(prefix)-2) + ")"
	})
	masked = strings.Replace(masked, "::", string([]rune{escapedColon, ':'}), -1)
	masked = strings.Replace(masked, ",:", string([]rune{escapedComma, ':'}), -1)
	masked = strings.Replace(masked, "+:", string([]rune{escapedPlus, ':'}), -1)

	idx := 0
	for _, pairStr := range strings.Split(masked, ",") {
		origPairStr := str[idx : idx+len(pairStr)]
		idx += len(pairStr) + 1

		pair := strings.SplitN(pairStr, ":", 2)
		if len(pair) < 2 {
			errorExit("bind action not specified: " + origPairStr)
		}
		var key int
		if len(pair[0]) == 1 && pair[0][0] == escapedColon {
			key = ':' + tui.AltZ
		} else if len(pair[0]) == 1 && pair[0][0] == escapedComma {
			key = ',' + tui.AltZ
		} else if len(pair[0]) == 1 && pair[0][0] == escapedPlus {
			key = '+' + tui.AltZ
		} else {
			keys := parseKeyChords(pair[0], "key name required")
			key = firstKey(keys)
		}

		idx2 := len(pair[0]) + 1
		specs := strings.Split(pair[1], "+")
		actions := make([]action, 0, len(specs))
		appendAction := func(types ...actionType) {
			actions = append(actions, toActions(types...)...)
		}
		prevSpec := ""
		for specIndex, maskedSpec := range specs {
			spec := origPairStr[idx2 : idx2+len(maskedSpec)]
			idx2 += len(maskedSpec) + 1
			spec = prevSpec + spec
			specLower := strings.ToLower(spec)
			switch specLower {
			case "ignore":
				appendAction(actIgnore)
			case "beginning-of-line":
				appendAction(actBeginningOfLine)
			case "abort":
				appendAction(actAbort)
			case "accept":
				appendAction(actAccept)
			case "print-query":
				appendAction(actPrintQuery)
			case "backward-char":
				appendAction(actBackwardChar)
			case "backward-delete-char":
				appendAction(actBackwardDeleteChar)
			case "backward-word":
				appendAction(actBackwardWord)
			case "clear-screen":
				appendAction(actClearScreen)
			case "delete-char":
				appendAction(actDeleteChar)
			case "delete-char/eof":
				appendAction(actDeleteCharEOF)
			case "end-of-line":
				appendAction(actEndOfLine)
			case "cancel":
				appendAction(actCancel)
			case "forward-char":
				appendAction(actForwardChar)
			case "forward-word":
				appendAction(actForwardWord)
			case "jump":
				appendAction(actJump)
			case "jump-accept":
				appendAction(actJumpAccept)
			case "kill-line":
				appendAction(actKillLine)
			case "kill-word":
				appendAction(actKillWord)
			case "unix-line-discard", "line-discard":
				appendAction(actUnixLineDiscard)
			case "unix-word-rubout", "word-rubout":
				appendAction(actUnixWordRubout)
			case "yank":
				appendAction(actYank)
			case "backward-kill-word":
				appendAction(actBackwardKillWord)
			case "toggle-down":
				appendAction(actToggle, actDown)
			case "toggle-up":
				appendAction(actToggle, actUp)
			case "toggle-in":
				appendAction(actToggleIn)
			case "toggle-out":
				appendAction(actToggleOut)
			case "toggle-all":
				appendAction(actToggleAll)
			case "select-all":
				appendAction(actSelectAll)
			case "deselect-all":
				appendAction(actDeselectAll)
			case "toggle":
				appendAction(actToggle)
			case "down":
				appendAction(actDown)
			case "up":
				appendAction(actUp)
			case "page-up":
				appendAction(actPageUp)
			case "page-down":
				appendAction(actPageDown)
			case "half-page-up":
				appendAction(actHalfPageUp)
			case "half-page-down":
				appendAction(actHalfPageDown)
			case "previous-history":
				appendAction(actPreviousHistory)
			case "next-history":
				appendAction(actNextHistory)
			case "toggle-preview":
				appendAction(actTogglePreview)
			case "toggle-sort":
				appendAction(actToggleSort)
			case "preview-up":
				appendAction(actPreviewUp)
			case "preview-down":
				appendAction(actPreviewDown)
			case "preview-page-up":
				appendAction(actPreviewPageUp)
			case "preview-page-down":
				appendAction(actPreviewPageDown)
			default:
				t := isExecuteAction(specLower)
				if t == actIgnore {
					errorExit("unknown action: " + spec)
				} else {
					var offset int
					switch t {
					case actExecuteSilent:
						offset = len("execute-silent")
					case actExecuteMulti:
						offset = len("execute-multi")
					default:
						offset = len("execute")
					}
					if spec[offset] == ':' {
						if specIndex == len(specs)-1 {
							actions = append(actions, action{t: t, a: spec[offset+1:]})
						} else {
							prevSpec = spec + "+"
							continue
						}
					} else {
						actions = append(actions, action{t: t, a: spec[offset+1 : len(spec)-1]})
					}
				}
			}
			prevSpec = ""
		}
		keymap[key] = actions
	}
}

func isExecuteAction(str string) actionType {
	matches := executeRegexp.FindAllStringSubmatch(":"+str, -1)
	if matches == nil || len(matches) != 1 {
		return actIgnore
	}
	prefix := matches[0][1]
	if len(prefix) == 0 {
		prefix = matches[0][2]
	}
	switch prefix {
	case "execute":
		return actExecute
	case "execute-silent":
		return actExecuteSilent
	case "execute-multi":
		return actExecuteMulti
	}
	return actIgnore
}

func parseToggleSort(keymap map[int][]action, str string) {
	keys := parseKeyChords(str, "key name required")
	if len(keys) != 1 {
		errorExit("multiple keys specified")
	}
	keymap[firstKey(keys)] = toActions(actToggleSort)
}

func strLines(str string) []string {
	return strings.Split(strings.TrimSuffix(str, "\n"), "\n")
}

func parseSize(str string, maxPercent float64, label string) sizeSpec {
	var val float64
	percent := strings.HasSuffix(str, "%")
	if percent {
		val = atof(str[:len(str)-1])
		if val < 0 {
			errorExit(label + " must be non-negative")
		}
		if val > maxPercent {
			errorExit(fmt.Sprintf("%s too large (max: %d%%)", label, int(maxPercent)))
		}
	} else {
		if strings.Contains(str, ".") {
			errorExit(label + " (without %) must be a non-negative integer")
		}

		val = float64(atoi(str))
		if val < 0 {
			errorExit(label + " must be non-negative")
		}
	}
	return sizeSpec{val, percent}
}

func parseHeight(str string) sizeSpec {
	if util.IsWindows() {
		errorExit("--height options is currently not supported on Windows")
	}
	size := parseSize(str, 100, "height")
	return size
}

func parsePreviewWindow(opts *previewOpts, input string) {
	// Default
	opts.position = posRight
	opts.size = sizeSpec{50, true}
	opts.hidden = false
	opts.wrap = false

	tokens := strings.Split(input, ":")
	sizeRegex := regexp.MustCompile("^[0-9]+%?$")
	for _, token := range tokens {
		switch token {
		case "hidden":
			opts.hidden = true
		case "wrap":
			opts.wrap = true
		case "up", "top":
			opts.position = posUp
		case "down", "bottom":
			opts.position = posDown
		case "left":
			opts.position = posLeft
		case "right":
			opts.position = posRight
		default:
			if sizeRegex.MatchString(token) {
				opts.size = parseSize(token, 99, "window size")
			} else {
				errorExit("invalid preview window layout: " + input)
			}
		}
	}
	if !opts.size.percent && opts.size.size > 0 {
		// Adjust size for border
		opts.size.size += 2
		// And padding
		if opts.position == posLeft || opts.position == posRight {
			opts.size.size += 2
		}
	}
}

func parseMargin(margin string) [4]sizeSpec {
	margins := strings.Split(margin, ",")
	checked := func(str string) sizeSpec {
		return parseSize(str, 49, "margin")
	}
	switch len(margins) {
	case 1:
		m := checked(margins[0])
		return [4]sizeSpec{m, m, m, m}
	case 2:
		tb := checked(margins[0])
		rl := checked(margins[1])
		return [4]sizeSpec{tb, rl, tb, rl}
	case 3:
		t := checked(margins[0])
		rl := checked(margins[1])
		b := checked(margins[2])
		return [4]sizeSpec{t, rl, b, rl}
	case 4:
		return [4]sizeSpec{
			checked(margins[0]), checked(margins[1]),
			checked(margins[2]), checked(margins[3])}
	default:
		errorExit("invalid margin: " + margin)
	}
	return defaultMargin()
}

func parseOptions(opts *Options, allArgs []string) {
	var historyMax int
	if opts.History == nil {
		historyMax = defaultHistoryMax
	} else {
		historyMax = opts.History.maxSize
	}
	setHistory := func(path string) {
		h, e := NewHistory(path, historyMax)
		if e != nil {
			errorExit(e.Error())
		}
		opts.History = h
	}
	setHistoryMax := func(max int) {
		historyMax = max
		if historyMax < 1 {
			errorExit("history max must be a positive integer")
		}
		if opts.History != nil {
			opts.History.maxSize = historyMax
		}
	}
	validateJumpLabels := false
	for i := 0; i < len(allArgs); i++ {
		arg := allArgs[i]
		switch arg {
		case "-h", "--help":
			help(exitOk)
		case "-x", "--extended":
			opts.Extended = true
		case "-e", "--exact":
			opts.Fuzzy = false
		case "--extended-exact":
			// Note that we now don't have --no-extended-exact
			opts.Fuzzy = false
			opts.Extended = true
		case "+x", "--no-extended":
			opts.Extended = false
		case "+e", "--no-exact":
			opts.Fuzzy = true
		case "-q", "--query":
			opts.Query = nextString(allArgs, &i, "query string required")
		case "-f", "--filter":
			filter := nextString(allArgs, &i, "query string required")
			opts.Filter = &filter
		case "--literal":
			opts.Normalize = false
		case "--no-literal":
			opts.Normalize = true
		case "--algo":
			opts.FuzzyAlgo = parseAlgo(nextString(allArgs, &i, "algorithm required (v1|v2)"))
		case "--expect":
			opts.Expect = parseKeyChords(nextString(allArgs, &i, "key names required"), "key names required")
		case "--tiebreak":
			opts.Criteria = parseTiebreak(nextString(allArgs, &i, "sort criterion required"))
		case "--bind":
			parseKeymap(opts.Keymap, nextString(allArgs, &i, "bind expression required"))
		case "--color":
			spec := optionalNextString(allArgs, &i)
			if len(spec) == 0 {
				opts.Theme = tui.EmptyTheme()
			} else {
				opts.Theme = parseTheme(opts.Theme, spec)
			}
		case "--toggle-sort":
			parseToggleSort(opts.Keymap, nextString(allArgs, &i, "key name required"))
		case "-d", "--delimiter":
			opts.Delimiter = delimiterRegexp(nextString(allArgs, &i, "delimiter required"))
		case "-n", "--nth":
			opts.Nth = splitNth(nextString(allArgs, &i, "nth expression required"))
		case "--with-nth":
			opts.WithNth = splitNth(nextString(allArgs, &i, "nth expression required"))
		case "-s", "--sort":
			opts.Sort = optionalNumeric(allArgs, &i)
		case "+s", "--no-sort":
			opts.Sort = 0
		case "--tac":
			opts.Tac = true
		case "--no-tac":
			opts.Tac = false
		case "-i":
			opts.Case = CaseIgnore
		case "+i":
			opts.Case = CaseRespect
		case "-m", "--multi":
			opts.Multi = true
		case "+m", "--no-multi":
			opts.Multi = false
		case "--ansi":
			opts.Ansi = true
		case "--no-ansi":
			opts.Ansi = false
		case "--no-mouse":
			opts.Mouse = false
		case "+c", "--no-color":
			opts.Theme = nil
		case "+2", "--no-256":
			opts.Theme = tui.Default16
		case "--black":
			opts.Black = true
		case "--no-black":
			opts.Black = false
		case "--bold":
			opts.Bold = true
		case "--no-bold":
			opts.Bold = false
		case "--reverse":
			opts.Reverse = true
		case "--no-reverse":
			opts.Reverse = false
		case "--cycle":
			opts.Cycle = true
		case "--no-cycle":
			opts.Cycle = false
		case "--hscroll":
			opts.Hscroll = true
		case "--no-hscroll":
			opts.Hscroll = false
		case "--hscroll-off":
			opts.HscrollOff = nextInt(allArgs, &i, "hscroll offset required")
		case "--filepath-word":
			opts.FileWord = true
		case "--no-filepath-word":
			opts.FileWord = false
		case "--inline-info":
			opts.InlineInfo = true
		case "--no-inline-info":
			opts.InlineInfo = false
		case "--jump-labels":
			opts.JumpLabels = nextString(allArgs, &i, "label characters required")
			validateJumpLabels = true
		case "-1", "--select-1":
			opts.Select1 = true
		case "+1", "--no-select-1":
			opts.Select1 = false
		case "-0", "--exit-0":
			opts.Exit0 = true
		case "+0", "--no-exit-0":
			opts.Exit0 = false
		case "--read0":
			opts.ReadZero = true
		case "--no-read0":
			opts.ReadZero = false
		case "--print0":
			opts.Printer = func(str string) { fmt.Print(str, "\x00") }
		case "--no-print0":
			opts.Printer = func(str string) { fmt.Println(str) }
		case "--print-query":
			opts.PrintQuery = true
		case "--no-print-query":
			opts.PrintQuery = false
		case "--prompt":
			opts.Prompt = nextString(allArgs, &i, "prompt string required")
		case "--sync":
			opts.Sync = true
		case "--no-sync":
			opts.Sync = false
		case "--async":
			opts.Sync = false
		case "--no-history":
			opts.History = nil
		case "--history":
			setHistory(nextString(allArgs, &i, "history file path required"))
		case "--history-size":
			setHistoryMax(nextInt(allArgs, &i, "history max size required"))
		case "--no-header":
			opts.Header = []string{}
		case "--no-header-lines":
			opts.HeaderLines = 0
		case "--header":
			opts.Header = strLines(nextString(allArgs, &i, "header string required"))
		case "--header-lines":
			opts.HeaderLines = atoi(
				nextString(allArgs, &i, "number of header lines required"))
		case "--preview":
			opts.Preview.command = nextString(allArgs, &i, "preview command required")
		case "--no-preview":
			opts.Preview.command = ""
		case "--preview-window":
			parsePreviewWindow(&opts.Preview,
				nextString(allArgs, &i, "preview window layout required: [up|down|left|right][:SIZE[%]][:wrap][:hidden]"))
		case "--height":
			opts.Height = parseHeight(nextString(allArgs, &i, "height required: HEIGHT[%]"))
		case "--min-height":
			opts.MinHeight = nextInt(allArgs, &i, "height required: HEIGHT")
		case "--no-height":
			opts.Height = sizeSpec{}
		case "--no-margin":
			opts.Margin = defaultMargin()
		case "--no-border":
			opts.Bordered = false
		case "--border":
			opts.Bordered = true
		case "--margin":
			opts.Margin = parseMargin(
				nextString(allArgs, &i, "margin required (TRBL / TB,RL / T,RL,B / T,R,B,L)"))
		case "--tabstop":
			opts.Tabstop = nextInt(allArgs, &i, "tab stop required")
		case "--version":
			opts.Version = true
		default:
			if match, value := optString(arg, "--algo="); match {
				opts.FuzzyAlgo = parseAlgo(value)
			} else if match, value := optString(arg, "-q", "--query="); match {
				opts.Query = value
			} else if match, value := optString(arg, "-f", "--filter="); match {
				opts.Filter = &value
			} else if match, value := optString(arg, "-d", "--delimiter="); match {
				opts.Delimiter = delimiterRegexp(value)
			} else if match, value := optString(arg, "--prompt="); match {
				opts.Prompt = value
			} else if match, value := optString(arg, "-n", "--nth="); match {
				opts.Nth = splitNth(value)
			} else if match, value := optString(arg, "--with-nth="); match {
				opts.WithNth = splitNth(value)
			} else if match, _ := optString(arg, "-s", "--sort="); match {
				opts.Sort = 1 // Don't care
			} else if match, value := optString(arg, "--height="); match {
				opts.Height = parseHeight(value)
			} else if match, value := optString(arg, "--min-height="); match {
				opts.MinHeight = atoi(value)
			} else if match, value := optString(arg, "--toggle-sort="); match {
				parseToggleSort(opts.Keymap, value)
			} else if match, value := optString(arg, "--expect="); match {
				opts.Expect = parseKeyChords(value, "key names required")
			} else if match, value := optString(arg, "--tiebreak="); match {
				opts.Criteria = parseTiebreak(value)
			} else if match, value := optString(arg, "--color="); match {
				opts.Theme = parseTheme(opts.Theme, value)
			} else if match, value := optString(arg, "--bind="); match {
				parseKeymap(opts.Keymap, value)
			} else if match, value := optString(arg, "--history="); match {
				setHistory(value)
			} else if match, value := optString(arg, "--history-size="); match {
				setHistoryMax(atoi(value))
			} else if match, value := optString(arg, "--header="); match {
				opts.Header = strLines(value)
			} else if match, value := optString(arg, "--header-lines="); match {
				opts.HeaderLines = atoi(value)
			} else if match, value := optString(arg, "--preview="); match {
				opts.Preview.command = value
			} else if match, value := optString(arg, "--preview-window="); match {
				parsePreviewWindow(&opts.Preview, value)
			} else if match, value := optString(arg, "--margin="); match {
				opts.Margin = parseMargin(value)
			} else if match, value := optString(arg, "--tabstop="); match {
				opts.Tabstop = atoi(value)
			} else if match, value := optString(arg, "--hscroll-off="); match {
				opts.HscrollOff = atoi(value)
			} else if match, value := optString(arg, "--jump-labels="); match {
				opts.JumpLabels = value
			} else {
				errorExit("unknown option: " + arg)
			}
		}
	}

	if opts.HeaderLines < 0 {
		errorExit("header lines must be a non-negative integer")
	}

	if opts.HscrollOff < 0 {
		errorExit("hscroll offset must be a non-negative integer")
	}

	if opts.Tabstop < 1 {
		errorExit("tab stop must be a positive integer")
	}

	if len(opts.JumpLabels) == 0 {
		errorExit("empty jump labels")
	}

	if validateJumpLabels {
		for _, r := range opts.JumpLabels {
			if r < 32 || r > 126 {
				errorExit("non-ascii jump labels are not allowed")
			}
		}
	}
}

func postProcessOptions(opts *Options) {
	// Default actions for CTRL-N / CTRL-P when --history is set
	if opts.History != nil {
		if _, prs := opts.Keymap[tui.CtrlP]; !prs {
			opts.Keymap[tui.CtrlP] = toActions(actPreviousHistory)
		}
		if _, prs := opts.Keymap[tui.CtrlN]; !prs {
			opts.Keymap[tui.CtrlN] = toActions(actNextHistory)
		}
	}

	// Extend the default key map
	keymap := defaultKeymap()
	for key, actions := range opts.Keymap {
		for _, act := range actions {
			if act.t == actToggleSort {
				opts.ToggleSort = true
			}
		}
		keymap[key] = actions
	}
	opts.Keymap = keymap

	// If we're not using extended search mode, --nth option becomes irrelevant
	// if it contains the whole range
	if !opts.Extended || len(opts.Nth) == 1 {
		for _, r := range opts.Nth {
			if r.begin == rangeEllipsis && r.end == rangeEllipsis {
				opts.Nth = make([]Range, 0)
				return
			}
		}
	}
}

// ParseOptions parses command-line options
func ParseOptions() *Options {
	opts := defaultOptions()

	// Options from Env var
	words, _ := shellwords.Parse(os.Getenv("FZF_DEFAULT_OPTS"))
	if len(words) > 0 {
		parseOptions(opts, words)
	}

	// Options from command-line arguments
	parseOptions(opts, os.Args[1:])

	postProcessOptions(opts)
	return opts
}
