package edit

import (
	"fmt"
	"strings"
	"unicode"
	"unicode/utf8"

	"github.com/elves/elvish/util"
)

// Line editor builtins.

// Builtin records an editor builtin.
type Builtin struct {
	name string
	impl func(ed *Editor)
}

var builtins = []Builtin{
	// Command and insert mode
	{"start-insert", startInsert},
	{"start-command", startCommand},
	{"kill-line-left", killLineLeft},
	{"kill-line-right", killLineRight},
	{"kill-word-left", killWordLeft},
	{"kill-rune-left", killRuneLeft},
	{"kill-rune-right", killRuneRight},
	{"move-dot-left", moveDotLeft},
	{"move-dot-right", moveDotRight},
	{"move-dot-left-word", moveDotLeftWord},
	{"move-dot-right-word", moveDotRightWord},
	{"move-dot-sol", moveDotSOL},
	{"move-dot-eol", moveDotEOL},
	{"move-dot-up", moveDotUp},
	{"move-dot-down", moveDotDown},
	{"insert-last-word", insertLastWord},
	{"insert-key", insertKey},
	{"return-line", returnLine},
	{"smart-enter", smartEnter},
	{"return-eof", returnEOF},
	{"default-command", defaultCommand},
	{"default-insert", defaultInsert},

	// Completion mode
	{"complete-prefix-or-start-completion", completePrefixOrStartCompletion},
	{"start-completion", startCompletion},
	{"cancel-completion", cancelCompletion},
	{"select-cand-up", selectCandUp},
	{"select-cand-down", selectCandDown},
	{"select-cand-left", selectCandLeft},
	{"select-cand-right", selectCandRight},
	{"cycle-cand-right", cycleCandRight},
	{"accept-completion", acceptCompletion},
	{"default-completion", defaultCompletion},

	// Navigation mode
	{"start-navigation", startNavigation},
	{"select-nav-up", selectNavUp},
	{"select-nav-down", selectNavDown},
	{"ascend-nav", ascendNav},
	{"descend-nav", descendNav},
	{"trigger-nav-show-hidden", triggerNavShowHidden},
	{"default-navigation", defaultNavigation},

	// History mode
	{"start-history", startHistory},
	{"select-history-prev", selectHistoryPrev},
	{"select-history-next", selectHistoryNext},
	{"select-history-next-or-quit", selectHistoryNextOrQuit},
	{"default-history", defaultHistory},

	// History listing mode
	{"start-history-listing", startHistoryListing},
	{"default-history-listing", defaultHistoryListing},

	// Location mode
	{"start-location", startLocation},
	{"location-prev", locationPrev},
	{"location-next", locationNext},
	{"accept-location", acceptLocation},
	{"cancel-location", cancelLocation},
	{"location-default", locationDefault},

	// Misc
	{"redraw", redraw},
}

var builtinMap = map[string]Builtin{}

func init() {
	for _, b := range builtins {
		builtinMap[b.name] = b
	}
	for mode, table := range defaultBindings {
		keyBindings[mode] = map[Key]Caller{}
		for key, name := range table {
			caller, ok := builtinMap[name]
			if !ok {
				fmt.Println("bad name " + name)
			} else {
				keyBindings[mode][key] = caller
			}
		}
	}
}

type action struct {
	actionType
	returnValue LineRead
}

func startInsert(ed *Editor) {
	ed.mode = modeInsert
}

func defaultCommand(ed *Editor) {
	k := ed.lastKey
	ed.addTip("Unbound: %s", k)
}

func startCommand(ed *Editor) {
	ed.mode = modeCommand
}

func killLineLeft(ed *Editor) {
	sol := util.FindLastSOL(ed.line[:ed.dot])
	ed.line = ed.line[:sol] + ed.line[ed.dot:]
	ed.dot = sol
}

func killLineRight(ed *Editor) {
	eol := util.FindFirstEOL(ed.line[ed.dot:]) + ed.dot
	ed.line = ed.line[:ed.dot] + ed.line[eol:]
}

// NOTE(xiaq): A word is now defined as a series of non-whitespace chars.
func killWordLeft(ed *Editor) {
	if ed.dot == 0 {
		return
	}
	space := strings.LastIndexFunc(
		strings.TrimRightFunc(ed.line[:ed.dot], unicode.IsSpace),
		unicode.IsSpace) + 1
	ed.line = ed.line[:space] + ed.line[ed.dot:]
	ed.dot = space
}

func killRuneLeft(ed *Editor) {
	if ed.dot > 0 {
		_, w := utf8.DecodeLastRuneInString(ed.line[:ed.dot])
		ed.line = ed.line[:ed.dot-w] + ed.line[ed.dot:]
		ed.dot -= w
	} else {
		ed.flash()
	}
}

func killRuneRight(ed *Editor) {
	if ed.dot < len(ed.line) {
		_, w := utf8.DecodeRuneInString(ed.line[ed.dot:])
		ed.line = ed.line[:ed.dot] + ed.line[ed.dot+w:]
	} else {
		ed.flash()
	}
}

func moveDotLeft(ed *Editor) {
	_, w := utf8.DecodeLastRuneInString(ed.line[:ed.dot])
	ed.dot -= w
}

func moveDotRight(ed *Editor) {
	_, w := utf8.DecodeRuneInString(ed.line[ed.dot:])
	ed.dot += w
}

func moveDotLeftWord(ed *Editor) {
	if ed.dot == 0 {
		return
	}
	space := strings.LastIndexFunc(
		strings.TrimRightFunc(ed.line[:ed.dot], unicode.IsSpace),
		unicode.IsSpace) + 1
	ed.dot = space
}

func moveDotRightWord(ed *Editor) {
	// Move to first space
	p := strings.IndexFunc(ed.line[ed.dot:], unicode.IsSpace)
	if p == -1 {
		ed.dot = len(ed.line)
		return
	}
	ed.dot += p
	// Move to first nonspace
	p = strings.IndexFunc(ed.line[ed.dot:], notSpace)
	if p == -1 {
		ed.dot = len(ed.line)
		return
	}
	ed.dot += p
}

func notSpace(r rune) bool {
	return !unicode.IsSpace(r)
}

func moveDotSOL(ed *Editor) {
	sol := util.FindLastSOL(ed.line[:ed.dot])
	ed.dot = sol
}

func moveDotEOL(ed *Editor) {
	eol := util.FindFirstEOL(ed.line[ed.dot:]) + ed.dot
	ed.dot = eol
}

func moveDotUp(ed *Editor) {
	sol := util.FindLastSOL(ed.line[:ed.dot])
	if sol == 0 {
		ed.flash()
		return
	}
	prevEOL := sol - 1
	prevSOL := util.FindLastSOL(ed.line[:prevEOL])
	width := WcWidths(ed.line[sol:ed.dot])
	ed.dot = prevSOL + len(TrimWcWidth(ed.line[prevSOL:prevEOL], width))
}

func moveDotDown(ed *Editor) {
	eol := util.FindFirstEOL(ed.line[ed.dot:]) + ed.dot
	if eol == len(ed.line) {
		ed.flash()
		return
	}
	nextSOL := eol + 1
	nextEOL := util.FindFirstEOL(ed.line[nextSOL:]) + nextSOL
	sol := util.FindLastSOL(ed.line[:ed.dot])
	width := WcWidths(ed.line[sol:ed.dot])
	ed.dot = nextSOL + len(TrimWcWidth(ed.line[nextSOL:nextEOL], width))
}

func insertLastWord(ed *Editor) {
	_, lastLine, err := ed.store.LastCmd(-1, "", true)
	if err == nil {
		ed.insertAtDot(lastWord(lastLine))
	} else {
		ed.addTip("db error: %s", err.Error())
	}
}

func lastWord(s string) string {
	s = strings.TrimRightFunc(s, unicode.IsSpace)
	i := strings.LastIndexFunc(s, unicode.IsSpace) + 1
	return s[i:]
}

func insertKey(ed *Editor) {
	k := ed.lastKey
	ed.insertAtDot(string(k.Rune))
}

func returnLine(ed *Editor) {
	ed.nextAction = action{exitReadLine, LineRead{Line: ed.line}}
}

func smartEnter(ed *Editor) {
	if ed.parseErrorAtEnd {
		// There is a parsing error at the end. Insert a newline and copy
		// indents from previous line.
		indent := findLastIndent(ed.line[:ed.dot])
		ed.insertAtDot("\n" + indent)
	} else {
		returnLine(ed)
	}
}

func findLastIndent(s string) string {
	line := s[util.FindLastSOL(s):]
	trimmed := strings.TrimLeft(line, " \t")
	return line[:len(line)-len(trimmed)]
}

func returnEOF(ed *Editor) {
	if len(ed.line) == 0 {
		ed.nextAction = action{exitReadLine, LineRead{EOF: true}}
	}
}

func selectCandUp(ed *Editor) {
	ed.completion.prev(false)
}

func selectCandDown(ed *Editor) {
	ed.completion.next(false)
}

func selectCandLeft(ed *Editor) {
	if c := ed.completion.current - ed.completionLines; c >= 0 {
		ed.completion.current = c
	}
}

func selectCandRight(ed *Editor) {
	if c := ed.completion.current + ed.completionLines; c < len(ed.completion.candidates) {
		ed.completion.current = c
	}
}

func cycleCandRight(ed *Editor) {
	ed.completion.next(true)
}

func cancelCompletion(ed *Editor) {
	ed.completion = nil
	ed.mode = modeInsert
}

func defaultInsert(ed *Editor) {
	k := ed.lastKey
	if k.Mod == 0 && k.Rune > 0 && unicode.IsGraphic(k.Rune) {
		insertKey(ed)
	} else {
		ed.addTip("Unbound: %s", k)
	}
}

func acceptCompletion(ed *Editor) {
	ed.acceptCompletion()
	ed.mode = modeInsert
}

func defaultCompletion(ed *Editor) {
	acceptCompletion(ed)
	ed.nextAction = action{actionType: reprocessKey}
}

func startNavigation(ed *Editor) {
	ed.mode = modeNavigation
	ed.navigation = newNavigation()
}

func selectNavUp(ed *Editor) {
	ed.navigation.prev()
}

func selectNavDown(ed *Editor) {
	ed.navigation.next()
}

func ascendNav(ed *Editor) {
	ed.navigation.ascend()
}

func descendNav(ed *Editor) {
	ed.navigation.descend()
}

func triggerNavShowHidden(ed *Editor) {
	ed.navigation.showHidden = !ed.navigation.showHidden
	ed.navigation.refresh()
}

func defaultNavigation(ed *Editor) {
	ed.mode = modeInsert
	ed.navigation = nil
}

func startHistory(ed *Editor) {
	ed.history.prefix = ed.line[:ed.dot]
	ed.history.current = -1
	if ed.prevHistory() {
		ed.mode = modeHistory
	} else {
		ed.addTip("no matching history item")
	}
}

func selectHistoryPrev(ed *Editor) {
	ed.prevHistory()
}

func selectHistoryNext(ed *Editor) {
	ed.nextHistory()
}

func selectHistoryNextOrQuit(ed *Editor) {
	if !ed.nextHistory() {
		ed.mode = modeInsert
	}
}

func defaultHistory(ed *Editor) {
	ed.acceptHistory()
	ed.mode = modeInsert
	ed.nextAction = action{actionType: reprocessKey}
}

func startHistoryListing(ed *Editor) {
	if ed.store == nil {
		ed.notify("store not connected")
		return
	}
	hl, err := newHistoryListing(ed.store)
	if err != nil {
		ed.notify("%s", err)
		return
	}
	ed.historyListing = hl
	ed.mode = modeHistoryListing
}

func defaultHistoryListing(ed *Editor) {
	ed.mode = modeInsert
	ed.historyListing = nil
	ed.nextAction = action{actionType: reprocessKey}
}

func redraw(ed *Editor) {
	ed.refresh(true, true)
}