package textobject

import (
	"git.gophernest.net/azpect/TextEditor/internal/action"
	"git.gophernest.net/azpect/TextEditor/internal/core"
)

// Word implements text object for words (iw/aw)
type Word struct{}

func (to Word) GetRange(m action.Model, cursor core.Position, modifier string) (core.Position, core.Position, core.MotionType) {
	buf := m.ActiveBuffer()
	line := buf.Line(cursor.Line)

	// Find word boundaries
	start := findWordStart(line, cursor.Col)
	end := findWordEnd(line, cursor.Col, modifier == "a")

	// Word object's don't span lines
	start.Line = cursor.Line
	end.Line = cursor.Line

	return start, end, core.CharwiseInclusive
}

// Word implements text object for WORDs (iW/aW)
type WORD struct{}

func (to WORD) GetRange(m action.Model, cursor core.Position, modifier string) (core.Position, core.Position, core.MotionType) {
	buf := m.ActiveBuffer()
	line := buf.Line(cursor.Line)

	// Find word boundaries
	start := findWORDStart(line, cursor.Col)
	end := findWORDEnd(line, cursor.Col, modifier == "a")

	// Word object's don't span lines
	start.Line = cursor.Line
	end.Line = cursor.Line

	return start, end, core.CharwiseInclusive
}

// isWordChar: Returns true if the character is a word character (alphanumeric
// or underscore). COPIED FROM internal/motion/word.go
func isWordChar(c byte) bool {
	return (c >= 'a' && c <= 'z') ||
		(c >= 'A' && c <= 'Z') ||
		(c >= '0' && c <= '9') ||
		c == '_'
}

func findWordStart(line string, col int) core.Position {
	if col >= len(line) || col < 0 {
		return core.Position{Line: 0, Col: 0}
	}

	curChar := line[col]

	// Don't start on whitespace (shouldn't happen for text objects)
	if curChar == ' ' || curChar == '\t' {
		return core.Position{Line: 0, Col: col}
	}

	// Determine if we're on word char or punctuation
	onWordChar := isWordChar(curChar)

	// Move backwards while in the same character class
	i := col
	for i > 0 {
		prevChar := line[i-1]

		// Stop at whitespace
		if prevChar == ' ' || prevChar == '\t' {
			break
		}

		// Stop if character class changes
		if isWordChar(prevChar) != onWordChar {
			break
		}

		i--
	}

	return core.Position{Line: 0, Col: i}
}

func findWordEnd(line string, col int, includeWhitespace bool) core.Position {
	if col >= len(line) || col < 0 {
		return core.Position{Line: 0, Col: 0}
	}

	curChar := line[col]

	// Don't start on whitespace
	if curChar == ' ' || curChar == '\t' {
		return core.Position{Line: 0, Col: col}
	}

	// Determine if we're on word char or punctuation
	onWordChar := isWordChar(curChar)

	// Move forward while in the same character class
	i := col
	for i < len(line) {
		c := line[i]

		// Stop at whitespace
		if c == ' ' || c == '\t' {
			break
		}

		// Stop if character class changes
		if isWordChar(c) != onWordChar {
			break
		}

		i++
	}

	// i is now one past the end, so back up
	i--

	// If including whitespace, skip trailing spaces/tabs
	if includeWhitespace {
		i++ // Move forward to whitespace
		for i < len(line) && (line[i] == ' ' || line[i] == '\t') {
			i++
		}
		i-- // Back to last whitespace
	}

	return core.Position{Line: 0, Col: i}
}

func findWORDStart(line string, col int) core.Position {
	if col >= len(line) || col < 0 {
		return core.Position{Line: 0, Col: 0}
	}

	curChar := line[col]

	// Don't start on whitespace (shouldn't happen for text objects)
	if curChar == ' ' || curChar == '\t' {
		return core.Position{Line: 0, Col: col}
	}

	// For WORD, all non-whitespace is one class
	// Just move backwards until we hit whitespace or start of line
	i := col
	for i > 0 {
		prevChar := line[i-1]

		// Stop at whitespace
		if prevChar == ' ' || prevChar == '\t' {
			break
		}

		i--
	}

	return core.Position{Line: 0, Col: i}
}

func findWORDEnd(line string, col int, includeWhitespace bool) core.Position {
	if col >= len(line) || col < 0 {
		return core.Position{Line: 0, Col: 0}
	}

	curChar := line[col]

	// Don't start on whitespace
	if curChar == ' ' || curChar == '\t' {
		return core.Position{Line: 0, Col: col}
	}

	// For WORD, all non-whitespace is one class
	// Move forward until we hit whitespace or end of line
	i := col
	for i < len(line) {
		c := line[i]

		// Stop at whitespace
		if c == ' ' || c == '\t' {
			break
		}

		i++
	}

	// i is now one past the end, so back up
	i--

	// If including whitespace, skip trailing spaces/tabs
	if includeWhitespace {
		i++ // Move forward to whitespace
		for i < len(line) && (line[i] == ' ' || line[i] == '\t') {
			i++
		}
		i-- // Back to last whitespace
	}

	return core.Position{Line: 0, Col: i}
}