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

func indexToCoord(i, c, n int) (x, y int) {
	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
		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) formatChoices(currentWord string, terminalWidth, terminalHeight int) string {
	var buf strings.Builder
	l, cursor := c.choices.Len(), c.choices.Cursor()
	if l == 0 {
		return ""
	}

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

	maxCol := min(max(terminalWidth/maxLen, 1), 5)
	lines := l / maxCol
	if l%maxCol > 0 {
		lines++
	}
	lineMin, lineMax := 0, lines-1
	var isPartial bool
	if isPartial = terminalHeight < lines; isPartial {
		_, cursorLine := indexToCoord(cursor, maxCol, l)
		if cursorLine < terminalHeight {
			lineMax = min(terminalHeight, lines) - 1
		} else {
			lineMin, lineMax = cursorLine+1-min(terminalHeight, lines), cursorLine
		}
	}

	colWith := terminalWidth / maxCol
	if colWith > maxLen {
		colWith = (colWith + maxLen) >> 1
	}
	for y := lineMin; y <= lineMax; y++ {
		if y > 0 {
			buf.WriteRune('\n')
		}
		for x := 0; x < maxCol; x++ {
			i := coordToIndex(x, y, maxCol, l)
			if i >= 0 {
				word := choices[i]
				realSize, displaySize := len([]rune(word)), atom.VisibleWidth(word)
				size := maxLen + 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, lines)
		buf.WriteRune('\n')
		buf.WriteString(format.Apply(position, "bg_l_cyan", "black"))
	}

	return buf.String()
}