package action

import (
	"strings"

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

// EnterInsert implements Action (i)
type EnterInsert struct {
	Count int
}

// EnterInsert.Execute: Enters insert mode at the cursor position (i key).
func (a EnterInsert) Execute(m Model) tea.Cmd {
	// Start recording
	m.SetInsertRecording(a.Count, a)
	m.SetMode(core.InsertMode)
	return nil
}

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

// EnterInsertAfter implements Action (a)
type EnterInsertAfter struct {
	Count int
}

// EnterInsertAfter.Execute: Enters insert mode after the cursor position (a key).
func (a EnterInsertAfter) Execute(m Model) tea.Cmd {
	win := m.ActiveWindow()
	win.SetCursorCol(win.Cursor.Col + 1)

	// Start recording
	m.SetInsertRecording(a.Count, a)
	m.SetMode(core.InsertMode)
	return nil
}

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

// EnterInsertLineStart implements Action (I)
type EnterInsertLineStart struct {
	Count int
}

// EnterInsertLineStart.Execute: Enters insert mode at the start of the line (I key).
func (a EnterInsertLineStart) Execute(m Model) tea.Cmd {
	win := m.ActiveWindow()
	win.SetCursorCol(0)

	// Start recording
	m.SetInsertRecording(a.Count, a)
	m.SetMode(core.InsertMode)
	return nil
}

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

// EnterInsertLineEnd implements Action (A)
type EnterInsertLineEnd struct {
	Count int
}

// EnterInsertLineEnd.Execute: Enters insert mode at the end of the line (A key).
func (a EnterInsertLineEnd) Execute(m Model) tea.Cmd {
	win := m.ActiveWindow()
	buf := m.ActiveBuffer()
	win.SetCursorCol(buf.Lines[win.Cursor.Line].Len())

	// Start recording
	m.SetInsertRecording(a.Count, a)
	m.SetMode(core.InsertMode)
	return nil
}

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

// OpenLineBelow implements Action (o)
type OpenLineBelow struct {
	Count int
}

// OpenLineBelow.Execute: Opens a new line below the cursor and enters insert mode (o key).
func (a OpenLineBelow) Execute(m Model) tea.Cmd {
	win := m.ActiveWindow()
	buf := m.ActiveBuffer()

	pos := win.Cursor.Line

	if pos >= buf.LineCount() {
		buf.InsertLine(buf.LineCount(), "")
	} else {
		buf.InsertLine(pos+1, "")
	}

	win.SetCursorPos(win.Cursor.Line+1, 0)

	// Start recording
	m.SetInsertRecording(a.Count, a)
	m.SetMode(core.InsertMode)
	return nil
}

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

// OpenLineAbove implements Action (O)
type OpenLineAbove struct {
	Count int
}

// OpenLineAbove.Execute: Opens a new line above the cursor and enters insert mode (O key).
func (a OpenLineAbove) Execute(m Model) tea.Cmd {
	win := m.ActiveWindow()
	buf := m.ActiveBuffer()

	pos := win.Cursor.Line
	buf.InsertLine(pos, "")
	win.SetCursorCol(0)

	// Start recording
	m.SetInsertRecording(a.Count, a)
	m.SetMode(core.InsertMode)
	return nil
}

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

// --- Insert mode edit actions ---

// InsertChar inserts a single character (or rune sequence) at the cursor
type InsertChar struct {
	Char string
}

// InsertChar.Execute: Inserts a single character at the cursor position.
func (a InsertChar) Execute(m Model) tea.Cmd {
	win := m.ActiveWindow()
	buf := m.ActiveBuffer()

	x, y := win.Cursor.Col, win.Cursor.Line
	l := buf.Line(y)
	if x < len(l) {
		buf.SetLine(y, l[:x]+a.Char+l[x:])
	} else {
		buf.SetLine(y, l+a.Char)
	}
	win.SetCursorCol(x + len(a.Char))
	return nil
}

// InsertNewline splits the current line at the cursor (enter key)
type InsertNewline struct{}

// InsertNewline.Execute: Splits the current line at the cursor (Enter key).
func (a InsertNewline) Execute(m Model) tea.Cmd {
	win := m.ActiveWindow()
	buf := m.ActiveBuffer()

	x, y := win.Cursor.Col, win.Cursor.Line
	l := buf.Line(y)
	if x == len(l) {
		buf.InsertLine(y+1, "")
	} else {
		buf.SetLine(y, l[:x])
		buf.InsertLine(y+1, l[x:])
	}
	win.SetCursorPos(y+1, 0)
	return nil
}

// InsertBackspace deletes the character before the cursor
type InsertBackspace struct{}

// InsertBackspace.Execute: Deletes the character before the cursor (Backspace key).
func (a InsertBackspace) Execute(m Model) tea.Cmd {
	win := m.ActiveWindow()
	buf := m.ActiveBuffer()

	x, y := win.Cursor.Col, win.Cursor.Line
	l := buf.Line(y)
	if x > 0 {
		buf.SetLine(y, l[:x-1]+l[x:])
		win.SetCursorCol(x - 1)
	} else if y > 0 {
		prevLine := buf.Line(y - 1)
		newX := len(prevLine)
		buf.SetLine(y-1, prevLine+l)
		buf.DeleteLine(y)
		win.SetCursorPos(y-1, newX)
	}
	return nil
}

// InsertDelete deletes the character under/after the cursor (delete key)
type InsertDelete struct{}

// InsertDelete.Execute: Deletes the character at the cursor position (Delete key).
func (a InsertDelete) Execute(m Model) tea.Cmd {
	win := m.ActiveWindow()
	buf := m.ActiveBuffer()

	x, y := win.Cursor.Col, win.Cursor.Line
	l := buf.Line(y)
	if x == len(l) && y < buf.LineCount()-1 {
		nextLine := buf.Line(y + 1)
		buf.SetLine(y, l+nextLine)
		buf.DeleteLine(y + 1)
	} else if x < len(l) {
		buf.SetLine(y, l[:x]+l[x+1:])
	}
	return nil
}

// InsertTab inserts spaces equal to the tab size
type InsertTab struct{}

// InsertTab.Execute: Inserts spaces equal to the tab size (Tab key).
func (a InsertTab) Execute(m Model) tea.Cmd {
	win := m.ActiveWindow()
	buf := m.ActiveBuffer()

	x, y := win.Cursor.Col, win.Cursor.Line
	l := buf.Line(y)
	tabs := strings.Repeat(" ", m.Settings().TabStop)
	if x < len(l) {
		buf.SetLine(y, l[:x]+tabs+l[x:])
	} else {
		buf.SetLine(y, l+tabs)
	}
	win.SetCursorCol(x + len(tabs))
	return nil
}

// InsertDeletePreviousWord deletes the word before the cursor (ctrl+w)
type InsertDeletePreviousWord struct{}

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

// isPunctuation: Returns true if the character is punctuation (not whitespace
// and not a word character).
func isPunctuation(c byte) bool {
	return c != ' ' && c != '\t' && !isWordChar(c)
}

// InsertDeletePreviousWord.Execute: Deletes the word before the cursor (Ctrl+W).
func (a InsertDeletePreviousWord) Execute(m Model) tea.Cmd {
	win := m.ActiveWindow()
	buf := m.ActiveBuffer()

	x, y := win.Cursor.Col, win.Cursor.Line
	line := buf.Line(y)

	// At start of line: merge with previous line (same as backspace)
	if x == 0 {
		if y > 0 {
			prevLine := buf.Line(y - 1)
			newX := len(prevLine)
			buf.SetLine(y-1, prevLine+line)
			buf.DeleteLine(y)
			win.SetCursorPos(y-1, newX)
		}
		return nil
	}

	// Scan backwards to find the new cursor position (don't mutate yet)
	newX := x

	// If we are on puncuation, we should just skip them all and quit
	if isPunctuation(line[newX-1]) {
		for newX > 0 && isPunctuation(line[newX-1]) {
			newX--
		}

		buf.SetLine(y, line[:newX]+line[x:])
		win.SetCursorCol(newX)

		return nil
	}

	// Skip whitespace immediately before the cursor
	for newX > 0 && (line[newX-1] == ' ' || line[newX-1] == '\t') {
		newX--
	}

	// Skip the word characters before the cursor
	for newX > 0 && isWordChar(line[newX-1]) {
		newX--
	}

	// Delete everything from newX up to x in one operation
	buf.SetLine(y, line[:newX]+line[x:])
	win.SetCursorCol(newX)

	return nil
}