package motion

import "git.gophernest.net/azpect/TextEditor/internal/core"

// Delimiter matching helpers operate on byte-indexed columns, which matches the
// rest of the editor cursor model.

func isDelimiter(ch byte) bool {
	switch ch {
	case '{', '}', '[', ']', '(', ')':
		return true
	default:
		return false
	}
}

func isOpeningDelimiter(ch byte) bool {
	return ch == '{' || ch == '[' || ch == '('
}

func getOppositeDelimiter(ch byte) (byte, bool) {
	switch ch {
	case '{':
		return '}', true
	case '}':
		return '{', true
	case '[':
		return ']', true
	case ']':
		return '[', true
	case '(':
		return ')', true
	case ')':
		return '(', true
	default:
		return 0, false
	}
}

func findDelimiterOnLine(line string, startCol int) (int, byte, bool) {
	if len(line) == 0 {
		return 0, 0, false
	}

	col := max(0, startCol)
	for col < len(line) {
		ch := line[col]
		if isDelimiter(ch) {
			return col, ch, true
		}
		col++
	}

	return 0, 0, false
}

func findMatchingForward(buf *core.Buffer, line, col int, startDelim, matchDelim byte) (core.Position, bool) {
	depth := 0

	for y := line; y < buf.LineCount(); y++ {
		text := buf.Line(y)
		xStart := 0
		if y == line {
			xStart = col + 1
		}

		for x := xStart; x < len(text); x++ {
			ch := text[x]
			if ch == startDelim {
				depth++
				continue
			}

			if ch == matchDelim {
				if depth == 0 {
					return core.Position{Line: y, Col: x}, true
				}
				depth--
			}
		}
	}

	return core.Position{}, false
}

func findMatchingBackward(buf *core.Buffer, line, col int, startDelim, matchDelim byte) (core.Position, bool) {
	depth := 0

	for y := line; y >= 0; y-- {
		text := buf.Line(y)
		xStart := len(text) - 1
		if y == line {
			xStart = col - 1
		}

		for x := xStart; x >= 0; x-- {
			ch := text[x]
			if ch == startDelim {
				depth++
				continue
			}

			if ch == matchDelim {
				if depth == 0 {
					return core.Position{Line: y, Col: x}, true
				}
				depth--
			}
		}
	}

	return core.Position{}, false
}