package gfishline

import (
	"fmt"
	"slices"
	"strings"

	"gitea.zaclys.com/bvaudour/gob/format"
	"gitea.zaclys.com/bvaudour/gob/shell/console"
	"gitea.zaclys.com/bvaudour/gob/shell/console/atom"
)

func coordToIndex(x, y, c, n int) int {
	if x < 0 || x >= c || y < 0 {
		return -1
	}

	l, r := n/c, n%c
	switch {
	case (x < r && y >= l+1) || (x >= r && y >= l):
		return -1
	case r == 0:
		return x*l + y
	case x < r:
		return x*(l+1) + y
	default:
		return r*(l+1) + (x-r)*l + y
	}
}

func indexToCoord(i, c, n int) (x, y int) {
	if i < 0 || i >= n {
		return -1, -1
	}

	l, r := n/c, n%c
	switch {
	case r == 0:
		x, y = i/l, i%l
	case i < r*(l+1):
		x, y = i/(l+1), i%(l+1)
	default:
		j := i - r*(l+1)
		x, y = r+j/l, j%l
	}

	return
}

type CompleteFunc func(words []string, wordIndex int, isIndexSpace bool) (choices []string)

func NoCompletion(words []string, wordIndex int, isIndexSpace bool) (choices []string) {
	return
}

func DefaultCompletion(commands, options []string) CompleteFunc {
	return func(words []string, wordIndex int, isIndexSpace bool) (choices []string) {
		if isIndexSpace {
			if wordIndex <= 0 {
				return commands
			}
			return options
		}

		word, sl := words[wordIndex], options
		if wordIndex == 0 {
			sl = commands
		}

		for _, choice := range sl {
			if strings.HasPrefix(choice, word) {
				choices = append(choices, choice)
			}
		}

		return
	}
}

type completer struct {
	*splitter
	wordIndex int
	wordPos   int
	isInit    bool
	needAdd   bool
	choices   console.Cycler
}

func newCompleter(buffer string, cursor int, complete CompleteFunc) *completer {
	c := completer{
		splitter: newSplitter(buffer, cursor),
		isInit:   true,
	}

	wordIndex, wordCursor, isIndexSpace := c.compute()
	if isIndexSpace && wordCursor == 0 && wordIndex > 0 {
		isIndexSpace = false
		c.cursor--
	}

	choices := complete(c.words, wordIndex, isIndexSpace)
	slices.Sort(choices)
	if !isIndexSpace {
		current := c.words[wordIndex]
		if slices.Contains(choices, current) {
			choices = append([]string{current}, slices.DeleteFunc(choices, func(e string) bool { return e == current })...)
		}
	}
	choices = slices.Compact(choices)

	c.choices = atom.NewCycler(true, choices...)
	c.needAdd, c.wordIndex, c.wordPos = isIndexSpace, wordIndex, wordCursor

	return &c
}

func (c *completer) update(next string) {
	c.setWord(c.wordIndex, next)

	if c.isInit {
		c.cursor += 2
		if _, ok := c.space[c.wordIndex+1]; !ok {
			c.space[c.wordIndex+1] = " "
		}
		c.isInit = false
	}
}

func (c *completer) add(next string) {
	c.addWord(c.wordIndex, next, c.wordPos)
	c.isInit, c.needAdd = false, false
}

func (c *completer) set() (ok bool) {
	var next string
	if next, ok = console.FocusedElement(c.choices).Get(); !ok {
		return
	}

	if c.needAdd {
		c.add(next)
	} else {
		c.update(next)
	}

	return
}

func (c *completer) prev() bool { return c.choices.Prev() && c.set() }

func (c *completer) next() bool { return c.choices.Next() && c.set() }

func (c *completer) move(index int) bool { return c.choices.SetCursor(index) && c.set() }

func (c *completer) gridInfo(terminalWidth, terminalHeight int) (nbChoices, colWidth, nbCols, nbLines int, choices []string) {
	nbChoices = c.choices.Len()
	if nbChoices == 0 {
		return
	}

	var wordWidth int
	choices = make([]string, nbChoices)
	for i := 0; i < nbChoices; i++ {
		word, _ := c.choices.Index(i).Get()
		choices[i], wordWidth = word, max(atom.VisibleWidth(word)+1, wordWidth)
	}

	nbCols = min(max(terminalWidth/wordWidth, 1), 5)
	nbLines = nbChoices / nbCols
	if nbChoices%nbCols > 0 {
		nbLines++
	}

	colWidth = terminalWidth / nbCols
	if colWidth > wordWidth {
		colWidth = (colWidth + wordWidth) >> 1
	}

	return
}

func (c *completer) infoMove(terminalWidth, terminalHeight int) (nbCols, nbLines, nbChoices, x, y, r int) {
	nbChoices, _, nbCols, nbLines, _ = c.gridInfo(terminalWidth, terminalHeight)

	if nbChoices > 0 {
		i := c.choices.Cursor()
		if i < 0 || i >= nbChoices {
			x, y = -1, -1
		} else {
			x, y = indexToCoord(i, nbCols, nbChoices)
			r = nbChoices % nbCols
		}
	}

	return
}

func (c *completer) left(terminalWidth, terminalHeight int) bool {
	nbCols, nbLines, nbChoices, x, y, r := c.infoMove(terminalWidth, terminalHeight)
	if nbChoices == 0 || x < 0 {
		return false
	}

	switch {
	case x > 0:
		x--
	case y > 0:
		x, y = nbCols-1, y-1
	case r > 0:
		x, y = r-1, nbLines-1
	default:
		x, y = nbCols-1, nbLines-1
	}

	i := coordToIndex(x, y, nbCols, nbChoices)

	return i >= 0 && c.move(i)
}

func (c *completer) right(terminalWidth, terminalHeight int) bool {
	nbCols, nbLines, nbChoices, x, y, r := c.infoMove(terminalWidth, terminalHeight)
	if nbChoices == 0 || x < 0 {
		return false
	}
	fmt.Println("debug0:", x, y)

	if x < r-1 || (x < nbCols-1 && (r == 0 || y < nbLines-1)) {
		x++
	} else if y < nbLines-1 {
		x, y = 0, y+1
	} else {
		x, y = 0, 0
	}
	fmt.Println("debug1:", x, y)

	i := coordToIndex(x, y, nbCols, nbChoices)

	return i >= 0 && c.move(i)
}

func (c *completer) formatChoices(currentWord string, terminalWidth, terminalHeight int) string {
	nbChoices, colWidth, nbCols, nbLines, choices := c.gridInfo(terminalWidth, terminalHeight)
	if nbChoices == 0 {
		return ""
	}

	cursor := c.choices.Cursor()
	lineMin, lineMax := 0, nbLines-1
	var isPartial bool
	if isPartial = terminalHeight < nbLines; isPartial {
		_, cursorLine := indexToCoord(cursor, nbCols, nbChoices)
		lineMin = max(0, cursorLine-terminalHeight+1)
		lineMax = lineMin + terminalHeight - 1
	}

	var buf strings.Builder
	for y := lineMin; y <= lineMax; y++ {
		if y > 0 {
			buf.WriteRune('\n')
		}
		for x := 0; x < nbCols; x++ {
			i := coordToIndex(x, y, nbCols, nbChoices)
			if i >= 0 {
				word := choices[i]
				realSize, displaySize := len([]rune(word)), atom.VisibleWidth(word)
				size := colWidth + realSize - displaySize
				word = strings.TrimPrefix(format.Left(word, size), currentWord)
				if i == cursor {
					buf.WriteString(format.Apply(currentWord, "bg_l_white", "black", "bold", "underline"))
					buf.WriteString(format.Apply(word, "bg_l_white", "black"))
				} else {
					buf.WriteString(format.Apply(currentWord, "bold", "underline"))
					buf.WriteString(word)
				}
			}
		}
	}

	if isPartial {
		position := fmt.Sprintf("lignes %d à %d (%d)", lineMin+1, lineMax+1, nbLines)
		buf.WriteRune('\n')
		buf.WriteString(format.Apply(position, "bg_l_cyan", "black"))
	}

	return buf.String()
}