package operator

import (
	"git.gophernest.net/azpect/TextEditor/internal/action"
	"git.gophernest.net/azpect/TextEditor/internal/core"
	tea "github.com/charmbracelet/bubbletea"
)

// YankOperator implements Operator (y) - copies text to register in various modes.
type YankOperator struct{}

// YankOperator.Operate: Copies text to register based on the current mode and motion type.
func (o YankOperator) Operate(m action.Model, start, end core.Position, mtype core.MotionType) tea.Cmd {
	win := m.ActiveWindow()

	switch m.Mode() {
	case core.VisualMode:
		yankVisualMode(m, start, end)
	case core.VisualLineMode:
		yankVisualLineMode(m, start, end)
	case core.VisualBlockMode:
		yankVisualBlockMode(m, start, end)
	case core.NormalMode:
		yankNormalMode(m, start, end, mtype)
	default:
		m.SetCommandOutput(&core.CommandOutput{
			Lines:   []string{"'y' operator not yet implemented."},
			Inline:  true,
			IsError: true,
		})
	}

	// Normalize so cursor is set to the earlier position (important for backward motions)
	cursorPos := start
	if end.Line < start.Line || (end.Line == start.Line && end.Col < start.Col) {
		cursorPos = end
	}

	win.SetCursorCol(cursorPos.Col)
	win.SetCursorLine(cursorPos.Line)
	return nil
}

// Verify YankOperator implements DoublePresser
var _ action.DoublePresser = YankOperator{}

// YankOperator.DoublePress: Handles yy - copies Count entire lines to register.
func (o YankOperator) DoublePress(m action.Model, count int) tea.Cmd {
	win := m.ActiveWindow()
	buf := m.ActiveBuffer()

	y := win.Cursor.Line

	// If we have a higher value than lines remaining, we can only run so many times
	opCount := min(count, buf.LineCount()-y)

	var lines []string

	for i := range opCount {
		lines = append(lines, buf.Line(y+i))
	}

	// Put her in the register!
	m.UpdateDefaultRegister(core.LinewiseRegister, lines)

	return nil
}

// yankNormalMode: Copies text to register in normal mode based on motion type.
func yankNormalMode(m action.Model, start, end core.Position, mtype core.MotionType) {
	buf := m.ActiveBuffer()

	switch {
	case mtype.IsCharwise():
		line := buf.Line(start.Line)

		startX := min(start.Col, end.Col)
		endX := max(start.Col, end.Col)

		// Inclusive motions include the end character
		if mtype == core.CharwiseInclusive {
			endX++
		}

		endX = min(endX, len(line)) // Catch overflow

		cnt := line[startX:endX]
		m.UpdateDefaultRegister(core.CharwiseRegister, []string{cnt})

		win := m.ActiveWindow()
		win.SetCursorCol(startX)
		win.SetCursorLine(start.Line)

	case mtype == core.Linewise:
		// These don't need to be validated, they are validated before being passed into the function
		startY := min(start.Line, end.Line)
		endY := max(start.Line, end.Line)

		var cnt []string
		for i := startY; i <= endY; i++ {
			cnt = append(cnt, buf.Line(i))
		}
		m.UpdateDefaultRegister(core.LinewiseRegister, cnt)
	}
}

// yankVisualMode: Copies character-wise visual selection to register.
func yankVisualMode(m action.Model, start, end core.Position) {
	buf := m.ActiveBuffer()

	// Normalize so start is before end
	if start.Line > end.Line || (start.Line == end.Line && start.Col > end.Col) {
		start, end = end, start
	}

	// Single line selection
	if start.Line == end.Line {
		line := buf.Line(start.Line)
		endCol := min(end.Col+1, len(line)) // +1 because visual selection is inclusive
		startCol := min(start.Col, len(line))
		cnt := line[startCol:endCol]
		m.UpdateDefaultRegister(core.CharwiseRegister, []string{cnt})
		return
	}

	// Multi-line selection
	var content []string

	// First line: from start.Col to end of line
	firstLine := buf.Line(start.Line)
	startCol := min(start.Col, len(firstLine))
	content = append(content, firstLine[startCol:])

	// Middle lines: entire lines
	for y := start.Line + 1; y < end.Line; y++ {
		content = append(content, buf.Line(y))
	}

	// Last line: from beginning to end.Col (inclusive)
	lastLine := buf.Line(end.Line)
	endCol := min(end.Col+1, len(lastLine))
	content = append(content, lastLine[:endCol])

	m.UpdateDefaultRegister(core.CharwiseRegister, content)
}

// yankVisualLineMode: Copies line-wise visual selection to register.
func yankVisualLineMode(m action.Model, start, end core.Position) {
	buf := m.ActiveBuffer()

	// This shouldn't happen
	// if start.Col != end.Col {
	// 	m.SetCommandOutput(&core.CommandOutput{
	// 		Lines:   []string{"Start column and end column must match for linewise yank operations."},
	// 		Inline:  true,
	// 		IsError: true,
	// 	})
	// 	return
	// }

	// These don't need to be validated, they are validated before being passed into the function
	startY := min(start.Line, end.Line)
	endY := max(start.Line, end.Line)

	var cnt []string
	for i := startY; i <= endY; i++ {
		cnt = append(cnt, buf.Line(i))
	}
	m.UpdateDefaultRegister(core.LinewiseRegister, cnt)

}

// yankVisualBlockMode: Copies block-wise visual selection to register.
func yankVisualBlockMode(m action.Model, start, end core.Position) {
	buf := m.ActiveBuffer()

	// Normalize so startY <= endY and startX <= endX
	startY := min(start.Line, end.Line)
	endY := max(start.Line, end.Line)
	startX := min(start.Col, end.Col)
	endX := max(start.Col, end.Col) + 1 // +1 for inclusive

	var content []string

	for y := startY; y <= endY; y++ {
		line := buf.Line(y)

		// Handle lines shorter than the block selection
		if startX >= len(line) {
			content = append(content, "")
			continue
		}

		lineEndX := min(endX, len(line))
		content = append(content, line[startX:lineEndX])
	}

	m.UpdateDefaultRegister(core.BlockwiseRegister, content)
}