package document

import (
	"strings"
	"timshome.page/gilo/editor/highlight"
	"timshome.page/gilo/internal/gilo"
	"timshome.page/gilo/key"
	"unicode"
)

type Row struct {
	parent *Document
	chars  []rune
	render []rune
	Hl     []int
}

func newRow(parent *Document, s string) *Row {
	var chars []rune
	var render []rune

	for _, ch := range s {
		chars = append(chars, ch)
		render = append(render, ch)
	}

	return &Row{parent, chars, render, []int{}}
}

func (r *Row) Size() int {
	return len(r.chars)
}

// RenderSize is a convenient equivalent of row->rsize in kilo
func (r *Row) RenderSize() int {
	return len(r.render)
}

func (r *Row) Render(at *gilo.Point) string {
	return string(r.render[at.X:])
}

// RenderRune returns the array of runes in the current row. Unlike a string
// this will index how you expect with multi-byte characters
func (r *Row) RenderRune(at *gilo.Point) []rune {
	return r.render[at.X:]
}

func (r *Row) Search(query string) int {
	return strings.Index(string(r.render), query)
}

func (r *Row) insertRune(ch rune, at int) {
	// If insertion index is invalid, just
	// append the rune to the end of the array
	if at < 0 || at >= r.Size() {
		r.chars = append(r.chars, ch)
		r.update()

		return
	}

	var newSlice []rune

	// Split the character array at the insertion point
	start := r.chars[0:at]
	end := r.chars[at:r.Size()]

	// Splice it back together
	newSlice = append(newSlice, start...)
	newSlice = append(newSlice, ch)
	newSlice = append(newSlice, end...)

	r.chars = newSlice
	r.update()
}

func (r *Row) appendString(str string) {
	for _, ch := range str {
		r.chars = append(r.chars, ch)
	}

	r.update()
}

func (r *Row) deleteRune(at int) {
	if at < 0 || at >= r.Size() {
		return
	}

	var newSlice []rune

	// Split the character array at the insertion point
	start := r.chars[0:at]
	end := r.chars[at+1 : r.Size()] // Skip the index in question

	// Splice it back together
	newSlice = append(newSlice, start...)
	newSlice = append(newSlice, end...)

	r.chars = newSlice
	r.update()
}

func (r *Row) update() {
	r.render = r.render[:0]
	replacement := strings.Repeat(" ", gilo.TabSize)

	str := strings.ReplaceAll(string(r.chars), "\t", replacement)
	for _, ch := range str {
		r.render = append(r.render, ch)
	}

	r.updateSyntax()
}

// updateSyntax is the equivalent of editorUpdateSyntax in kilo
func (r *Row) updateSyntax() {
	i := 0
	s := r.parent.Syntax
	r.Hl = make([]int, r.RenderSize())
	for x := range r.Hl {
		r.Hl[x] = highlight.Normal
	}

	// Don't bother updating the syntax if there isn't any
	if s == nil {
		return
	}

	renderStr := string(r.render)
	keywords1 := s.Keywords1
	keywords2 := s.Keywords2

	var scsIndex int = -1
	scs := s.LineCommentStart
	if len(scs) > 0 {
		scsIndex = strings.Index(renderStr, scs)
	}

	prevSep := true
	inString := '0'
	for i < r.RenderSize() {
		ch := r.render[i]
		prevHl := highlight.Normal
		if i > 0 {
			prevHl = r.Hl[i-1]
		}

		ip1 := i + 1

		// Single line comments
		if inString == '0' && scsIndex == i {
			for j := scsIndex; j < r.RenderSize(); j++ {
				r.Hl[j] = highlight.Comment
			}
			break
		}

		// String literals
		if s.Flags&highlight.DoStrings == highlight.DoStrings {
			// At the start of a string literal
			if inString == '0' && (ch == '"' || ch == '\'') {
				inString = ch
				r.Hl[i] = highlight.String
				i++
				continue
			}

			// In an existing string
			if inString != '0' {
				r.Hl[i] = highlight.String

				// Handle when a quote is escaped inside a string
				if ch == '\\' && ip1 < r.RenderSize() {
					r.Hl[ip1] = highlight.String
					i += 2
					continue
				}

				// This quote mark matches the beginning of the string
				// so now the string is completed
				if ch == inString {
					inString = '0'
				}

				i++
				prevSep = true
				continue
			}
		}

		// Numeric literals
		if s.Flags&highlight.DoNumbers == highlight.DoNumbers {
			if (unicode.IsDigit(ch) && (prevSep || prevHl == highlight.Number)) ||
				(ch == '.' && prevHl == highlight.Number) {
				r.Hl[i] = highlight.Number
				i += 1
				prevSep = false
				continue
			}
		}

		// Keywords
		if prevSep {
			renderLen := r.RenderSize()

			for _, word := range keywords1 {
				wordLen := len(word)
				nextInd := i + wordLen
				if nextInd >= renderLen || renderStr[i:nextInd] != word {
					continue
				}

				if renderStr[i:renderLen] == word || key.IsSeparator(r.render[nextInd]) {
					for k := i; k < nextInd; k++ {
						r.Hl[k] = highlight.Keyword1
					}
					i += wordLen
					break
				}
			}

			for _, word := range keywords2 {
				wordLen := len(word)
				nextInd := i + wordLen
				if nextInd >= renderLen || renderStr[i:nextInd] != word {
					continue
				}

				if renderStr[i:renderLen] == word || key.IsSeparator(r.render[nextInd]) {
					for k := i; k < nextInd; k++ {
						r.Hl[k] = highlight.Keyword2
					}
					i += wordLen
					break
				}
			}
		}

		prevSep = key.IsSeparator(ch)
		i++
	}
}

func (r *Row) toString() string {
	return string(r.chars)
}

// CursorXToRenderX is the equivalent of editorRowCxToRx in kilo
func (r *Row) CursorXToRenderX(cursorX int) (renderX int) {
	renderX = 0

	for i := 0; i < cursorX; i++ {
		if r.chars[i] == '\t' {
			renderX += (gilo.TabSize - 1) - (renderX % gilo.TabSize)
		}

		renderX += 1
	}

	return renderX
}

// RenderXtoCursorX is the equivalent of editorRowRxToCx in kilo
func (r *Row) RenderXtoCursorX(renderX int) (cursorX int) {
	currentRenderX := 0
	cursorX = 0

	for cursorX = 0; cursorX < r.Size(); cursorX++ {
		if r.chars[cursorX] == '\t' {
			currentRenderX += (gilo.TabSize - 1) - (currentRenderX % gilo.TabSize)
		} else {
			currentRenderX += 1
		}

		if currentRenderX > renderX {
			return cursorX
		}
	}

	return cursorX
}