package action

import (
	"strings"

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

// Paste implements Action (p) - pastes after cursor
type Paste struct {
	Count int
}

// Paste.Execute: Pastes register content after the cursor position (p key).
func (a Paste) Execute(m Model) tea.Cmd {
	win := m.ActiveWindow()
	buf := m.ActiveBuffer()

	// Get reg
	reg, found := m.GetRegister('"')
	if !found {
		out := core.CommandOutput{
			Lines:   []string{"\"\" register is broken. Uh oh."},
			Inline:  true,
			IsError: true,
		}
		m.SetCommandOutput(&out)
		return nil
	}

	// Exit if blank
	if len(reg.Content) == 0 {
		return nil
	}

	switch reg.Type {
	case core.LinewiseRegister:
		{
			initY := win.Cursor.Line
			lines := reg.Content
			insertPos := initY + 1

			// Run count times
			for range a.Count {
				for _, line := range lines {
					buf.InsertLine(insertPos, line)
					insertPos++
				}
			}

			if buf.LineCount() > 1 {
				win.SetCursorLine(initY + 1)
			}
		}
	case core.CharwiseRegister:
		{
			lines := reg.Content

			if len(lines) == 0 {
				break
			}

			x := win.Cursor.Col
			y := win.Cursor.Line
			curLine := buf.Lines[y]
			insertAt := min(x+1, len(curLine))

			if len(lines) == 1 {
				// Single-line charwise paste
				cnt := strings.Repeat(lines[0], max(1, a.Count))
				newLine := curLine[:insertAt] + cnt + curLine[insertAt:]
				buf.SetLine(y, newLine)
				win.SetCursorCol(x + len(cnt))
			} else {
				// Multi-line charwise paste (e.g., from vi{ yank)
				suffix := curLine[insertAt:] // Save the part after cursor

				// For count > 1, we paste the content multiple times
				// Each paste continues from where the previous one ended
				var content strings.Builder
				for i := 0; i < a.Count; i++ {
					for j, line := range lines {
						if j > 0 {
							content.WriteString("\n")
						}
						content.WriteString(line)
					}
				}

				// Split the pasted content into lines
				pastedLines := strings.Split(content.String(), "\n")

				// First line: append to current line
				buf.SetLine(y, curLine[:insertAt]+pastedLines[0])

				// Middle lines: insert as new lines
				for i := 1; i < len(pastedLines); i++ {
					buf.InsertLine(y+i, pastedLines[i])
				}

				// Last line: append the suffix
				lastLineIdx := y + len(pastedLines) - 1
				buf.SetLine(lastLineIdx, buf.Lines[lastLineIdx]+suffix)

				// Set cursor to end of last pasted content (before suffix)
				win.SetCursorLine(lastLineIdx)
				win.SetCursorCol(len(buf.Lines[lastLineIdx]) - len(suffix) - 1)
			}
		}
	default:
		out := core.CommandOutput{
			Lines:   []string{"core.Register type is not implemented."},
			Inline:  true,
			IsError: true,
		}
		m.SetCommandOutput(&out)
	}

	return nil
}

// Ensure Paste implements Repeatable
var _ Repeatable = Paste{}

// Paste.WithCount: Returns a new Paste with the given count.
func (a Paste) WithCount(n int) Action {
	return Paste{Count: n}
}

// PasteBefore implements Action (P) - pastes before cursor
type PasteBefore struct {
	Count int
}

// PasteBefore.Execute: Pastes register content before the cursor position (P key).
func (a PasteBefore) Execute(m Model) tea.Cmd {
	win := m.ActiveWindow()
	buf := m.ActiveBuffer()

	// Get reg
	reg, found := m.GetRegister('"')
	if !found {
		out := core.CommandOutput{
			Lines:   []string{"\"\" register is broken. Uh oh."},
			Inline:  true,
			IsError: true,
		}
		m.SetCommandOutput(&out)
		return nil
	}

	switch reg.Type {
	case core.LinewiseRegister:
		{
			initY := win.Cursor.Line
			lines := reg.Content
			insertPos := initY // Leave here, this will effectively move the lines below

			// Run count times
			for range a.Count {
				for _, line := range lines {
					buf.InsertLine(insertPos, line)
					insertPos++
				}
			}
		}
	case core.CharwiseRegister:
		{
			lines := reg.Content

			if len(lines) == 0 {
				break
			}

			x := win.Cursor.Col
			y := win.Cursor.Line
			curLine := buf.Lines[y]
			insertAt := min(x, len(curLine))

			if len(lines) == 1 {
				// Single-line charwise paste before cursor
				cnt := strings.Repeat(lines[0], max(1, a.Count))
				newLine := curLine[:insertAt] + cnt + curLine[insertAt:]
				buf.SetLine(y, newLine)
				win.SetCursorCol(x + len(cnt))
			} else {
				// Multi-line charwise paste before cursor
				suffix := curLine[insertAt:] // Save the part after cursor

				// For count > 1, we paste the content multiple times
				// Each paste continues from where the previous one ended
				var content strings.Builder
				for i := 0; i < a.Count; i++ {
					for j, line := range lines {
						if j > 0 {
							content.WriteString("\n")
						}
						content.WriteString(line)
					}
				}

				// Split the pasted content into lines
				pastedLines := strings.Split(content.String(), "\n")

				// First line: insert at cursor position
				buf.SetLine(y, curLine[:insertAt]+pastedLines[0])

				// Middle lines: insert as new lines
				for i := 1; i < len(pastedLines); i++ {
					buf.InsertLine(y+i, pastedLines[i])
				}

				// Last line: append the suffix
				lastLineIdx := y + len(pastedLines) - 1
				buf.SetLine(lastLineIdx, buf.Lines[lastLineIdx]+suffix)

				// Set cursor to end of last pasted content (before suffix)
				win.SetCursorLine(lastLineIdx)
				win.SetCursorCol(len(buf.Lines[lastLineIdx]) - len(suffix) - 1)
			}
		}
	default:
		out := core.CommandOutput{
			Lines:   []string{"core.Register type is not implemented."},
			Inline:  true,
			IsError: true,
		}
		m.SetCommandOutput(&out)
	}

	return nil
}

// Ensure PasteBefore implements Repeatable
var _ Repeatable = PasteBefore{}

// PasteBefore.WithCount: Returns a new PasteBefore with the given count.
func (a PasteBefore) WithCount(n int) Action {
	return PasteBefore{Count: n}
}

// VisualPaste implements Action (p in visual mode) - replaces selection with register content
type VisualPaste struct {
	Count int
}

// VisualPaste.Execute: Replaces visual selection with register content (p in visual mode).
func (a VisualPaste) Execute(m Model) tea.Cmd {
	// Get register content to paste
	reg, found := m.GetRegister('"')
	if !found {
		out := core.CommandOutput{
			Lines:   []string{"\"\" register is broken. Uh oh."},
			Inline:  true,
			IsError: true,
		}
		m.SetCommandOutput(&out)
		return nil
	}

	mode := m.Mode()

	// Get selection bounds (normalize anchor and cursor)
	start, end := normalizeSelection(m)

	switch mode {
	case core.VisualMode:
		visualCharPaste(m, reg, start, end)
	case core.VisualBlockMode:
		visualBlockPaste(m, reg, start, end)
	case core.VisualLineMode:
		visualLinePaste(m, reg, start, end)
	}

	// Exit visual mode
	m.SetMode(core.NormalMode)

	return nil
}

// normalizeSelection: Returns start and end positions with start always before end.
func normalizeSelection(m Model) (core.Position, core.Position) {
	win := m.ActiveWindow()

	start := core.Position{Line: win.Anchor.Line, Col: win.Anchor.Col}
	end := core.Position{Line: win.Cursor.Line, Col: win.Cursor.Col}

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

	return start, end
}

// visualCharPaste: Handles paste operation in visual (character) mode.
func visualCharPaste(m Model, reg core.Register, start, end core.Position) {
	win := m.ActiveWindow()
	buf := m.ActiveBuffer()

	// First, extract the text that will be deleted (to save to register)
	deletedText := extractCharSelection(m, start, end)

	// Delete the selection
	deleteCharSelectionForPaste(m, start, end)

	// Insert the register content at start position
	if len(reg.Content) == 0 {
		// Empty register - just delete (already done)
	} else if reg.Type == core.CharwiseRegister {
		// Charwise paste: insert text at cursor position
		if len(reg.Content) == 1 {
			line := buf.Lines[start.Line]
			insertAt := min(start.Col, len(line))
			newLine := line[:insertAt] + reg.Content[0] + line[insertAt:]
			buf.SetLine(start.Line, newLine)

			// Cursor at end of pasted text
			win.SetCursorCol(insertAt + len(reg.Content[0]) - 1)
			win.SetCursorLine(start.Line)
		}
	} else if reg.Type == core.LinewiseRegister {
		// Linewise paste in visual char mode: replace selection with lines
		// Insert each line from register
		for i, content := range reg.Content {
			if i == 0 {
				// First line: insert at start position
				line := buf.Lines[start.Line]
				insertAt := min(start.Col, len(line))
				newLine := line[:insertAt] + content
				if len(reg.Content) == 1 {
					// Single line register - append rest of line
					newLine += line[insertAt:]
				}
				buf.SetLine(start.Line, newLine)
			} else {
				// Subsequent lines: insert new lines
				buf.InsertLine(start.Line+i, content)
			}
		}
		win.SetCursorLine(start.Line)
		win.SetCursorCol(start.Col)
	}

	// Update register with deleted text
	m.UpdateDefaultRegister(core.CharwiseRegister, []string{deletedText})
}

// visualBlockPaste: Handles paste operation in visual block mode.
func visualBlockPaste(m Model, reg core.Register, start, end core.Position) {
	win := m.ActiveWindow()
	buf := m.ActiveBuffer()

	startCol := min(start.Col, end.Col)
	endCol := max(start.Col, end.Col)

	// Extract deleted text (for register)
	var deletedLines []string
	for y := start.Line; y <= end.Line; y++ {
		line := buf.Lines[y]
		if startCol < len(line) {
			ec := min(endCol+1, len(line))
			deletedLines = append(deletedLines, line[startCol:ec])
		} else {
			deletedLines = append(deletedLines, "")
		}
	}

	// Delete the block selection
	for y := start.Line; y <= end.Line; y++ {
		line := buf.Lines[y]
		if startCol >= len(line) {
			continue
		}
		ec := min(endCol+1, len(line))
		buf.SetLine(y, line[:startCol]+line[ec:])
	}

	// Insert register content
	if len(reg.Content) > 0 {
		pasteContent := reg.Content[0]
		if reg.Type == core.LinewiseRegister && len(reg.Content) > 0 {
			pasteContent = reg.Content[0]
		}

		for y := start.Line; y <= end.Line; y++ {
			line := buf.Lines[y]
			insertAt := min(startCol, len(line))
			// Pad with spaces if needed
			for len(line) < insertAt {
				line += " "
			}
			newLine := line[:insertAt] + pasteContent + line[insertAt:]
			buf.SetLine(y, newLine)
		}
	}

	win.SetCursorLine(start.Line)
	win.SetCursorCol(startCol)

	// Update register with deleted block text (joined)
	m.UpdateDefaultRegister(core.CharwiseRegister, []string{strings.Join(deletedLines, "\n")})
}

// visualLinePaste: Handles paste operation in visual line mode.
func visualLinePaste(m Model, reg core.Register, start, end core.Position) {
	win := m.ActiveWindow()
	buf := m.ActiveBuffer()

	// Extract deleted lines (for register)
	var deletedLines []string
	for y := start.Line; y <= end.Line; y++ {
		deletedLines = append(deletedLines, buf.Lines[y])
	}

	// Delete the selected lines (from end to start to preserve indices)
	for y := end.Line; y >= start.Line; y-- {
		buf.DeleteLine(y)
	}

	// Insert register content
	if len(reg.Content) == 0 {
		// Empty register - ensure at least one empty line exists
		if buf.LineCount() == 0 {
			buf.InsertLine(0, "")
		}
	} else if reg.Type == core.LinewiseRegister {
		// Linewise register: insert each line
		insertPos := start.Line
		for _, content := range reg.Content {
			buf.InsertLine(insertPos, content)
			insertPos++
		}
	} else {
		// Charwise register: insert as a single line
		buf.InsertLine(start.Line, reg.Content[0])
	}

	// Ensure we have at least one line
	if buf.LineCount() == 0 {
		buf.InsertLine(0, "")
	}

	// core.Position cursor at start of pasted content
	y := start.Line
	if y >= buf.LineCount() {
		y = buf.LineCount() - 1
	}
	win.SetCursorLine(y)
	win.SetCursorCol(0)

	// Update register with deleted lines
	m.UpdateDefaultRegister(core.LinewiseRegister, deletedLines)
}

// extractCharSelection: Extracts text from a character selection range.
func extractCharSelection(m Model, start, end core.Position) string {
	buf := m.ActiveBuffer()

	if start.Line == end.Line {
		line := buf.Lines[start.Line]
		endCol := min(end.Col+1, len(line))
		startCol := min(start.Col, len(line))
		if startCol >= endCol {
			return ""
		}
		return line[startCol:endCol]
	}

	// Multi-line selection
	var result strings.Builder

	// First line: from start.Col to end
	firstLine := buf.Lines[start.Line]
	if start.Col < len(firstLine) {
		result.WriteString(firstLine[start.Col:])
	}
	result.WriteString("\n")

	// Middle lines: entire lines
	for y := start.Line + 1; y < end.Line; y++ {
		result.WriteString(buf.Lines[y])
		result.WriteString("\n")
	}

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

	return result.String()
}

// deleteCharSelectionForPaste: Deletes a character selection for paste operations.
func deleteCharSelectionForPaste(m Model, start, end core.Position) {
	win := m.ActiveWindow()
	buf := m.ActiveBuffer()

	if start.Line == end.Line {
		line := buf.Lines[start.Line]
		endCol := min(end.Col+1, len(line))
		buf.SetLine(start.Line, line[:start.Col]+line[endCol:])
	} else {
		startLine := buf.Lines[start.Line]
		endLine := buf.Lines[end.Line]

		prefix := ""
		if start.Col < len(startLine) {
			prefix = startLine[:start.Col]
		}

		suffix := ""
		if end.Col+1 < len(endLine) {
			suffix = endLine[end.Col+1:]
		}

		// Delete from end back to start to preserve indices
		for i := end.Line; i >= start.Line; i-- {
			buf.DeleteLine(i)
		}
		buf.InsertLine(start.Line, prefix+suffix)
	}

	win.SetCursorLine(start.Line)
	win.SetCursorCol(start.Col)
}

// Ensure VisualPaste implements Repeatable
var _ Repeatable = VisualPaste{}

// VisualPaste.WithCount: Returns a new VisualPaste with the given count.
func (a VisualPaste) WithCount(n int) Action {
	return VisualPaste{Count: n}
}