package tetris

import (
	"context"
	"strings"
	"testing"
	"time"

	tea "github.com/charmbracelet/bubbletea"

	"code.t-juice.club/torjus/oubliette/internal/shell"
	"code.t-juice.club/torjus/oubliette/internal/storage"
)

// newTestModel creates a model with a test session context.
func newTestModel(t *testing.T) (*model, *storage.MemoryStore) {
	t.Helper()
	store := storage.NewMemoryStore()
	sessID, _ := store.CreateSession(context.Background(), "127.0.0.1", "player", "tetris", "")
	sess := &shell.SessionContext{
		SessionID: sessID,
		Username:  "player",
		Store:     store,
	}
	m := newModel(sess, "normal")
	return m, store
}

// sendKey sends a single key message to the model and returns the command.
func sendKey(m *model, key string) tea.Cmd {
	var msg tea.KeyMsg
	switch key {
	case "enter":
		msg = tea.KeyMsg{Type: tea.KeyEnter}
	case "up":
		msg = tea.KeyMsg{Type: tea.KeyUp}
	case "down":
		msg = tea.KeyMsg{Type: tea.KeyDown}
	case "left":
		msg = tea.KeyMsg{Type: tea.KeyLeft}
	case "right":
		msg = tea.KeyMsg{Type: tea.KeyRight}
	case "space":
		msg = tea.KeyMsg{Type: tea.KeySpace}
	case "ctrl+c":
		msg = tea.KeyMsg{Type: tea.KeyCtrlC}
	default:
		if len(key) == 1 {
			msg = tea.KeyMsg{Type: tea.KeyRunes, Runes: []rune(key)}
		}
	}
	_, cmd := m.Update(msg)
	return cmd
}

// sendTick sends a tick message to the model.
func sendTick(m *model) tea.Cmd {
	_, cmd := m.Update(tickMsg(time.Now()))
	return cmd
}

// execCmds recursively executes tea.Cmd functions (including batches).
func execCmds(cmd tea.Cmd) {
	if cmd == nil {
		return
	}
	msg := cmd()
	if batch, ok := msg.(tea.BatchMsg); ok {
		for _, c := range batch {
			execCmds(c)
		}
	}
}

func TestTetrisShellName(t *testing.T) {
	sh := NewTetrisShell()
	if sh.Name() != "tetris" {
		t.Errorf("Name() = %q, want %q", sh.Name(), "tetris")
	}
	if sh.Description() == "" {
		t.Error("Description() should not be empty")
	}
}

func TestConfigString(t *testing.T) {
	cfg := map[string]any{
		"difficulty": "hard",
	}
	if got := configString(cfg, "difficulty", "normal"); got != "hard" {
		t.Errorf("configString() = %q, want %q", got, "hard")
	}
	if got := configString(cfg, "missing", "normal"); got != "normal" {
		t.Errorf("configString() = %q, want %q", got, "normal")
	}
	if got := configString(nil, "difficulty", "normal"); got != "normal" {
		t.Errorf("configString(nil) = %q, want %q", got, "normal")
	}
}

func TestTitleScreenRenders(t *testing.T) {
	m, _ := newTestModel(t)
	view := m.View()
	if !strings.Contains(view, "████") {
		t.Error("title screen should show TETRIS logo")
	}
	if !strings.Contains(view, "Press any key") {
		t.Error("title screen should show 'Press any key'")
	}
}

func TestTitleToGame(t *testing.T) {
	m, _ := newTestModel(t)
	if m.screen != screenTitle {
		t.Fatalf("expected screenTitle, got %d", m.screen)
	}

	sendKey(m, "enter")
	if m.screen != screenGame {
		t.Errorf("expected screenGame after keypress, got %d", m.screen)
	}
	if m.game == nil {
		t.Fatal("game should be initialized")
	}
}

func TestGameRenders(t *testing.T) {
	m, _ := newTestModel(t)
	sendKey(m, "enter") // start game

	view := m.View()
	if !strings.Contains(view, "|") {
		t.Error("game view should contain board borders")
	}
	if !strings.Contains(view, "SCORE") {
		t.Error("game view should show SCORE")
	}
	if !strings.Contains(view, "LEVEL") {
		t.Error("game view should show LEVEL")
	}
	if !strings.Contains(view, "LINES") {
		t.Error("game view should show LINES")
	}
	if !strings.Contains(view, "NEXT") {
		t.Error("game view should show NEXT")
	}
}

// --- Pure game logic tests ---

func TestNewGame(t *testing.T) {
	g := newGame(0)
	if g.gameOver {
		t.Error("new game should not be game over")
	}
	if g.score != 0 {
		t.Errorf("initial score = %d, want 0", g.score)
	}
	if g.level != 0 {
		t.Errorf("initial level = %d, want 0", g.level)
	}
	if g.lines != 0 {
		t.Errorf("initial lines = %d, want 0", g.lines)
	}
}

func TestNewGameHardLevel(t *testing.T) {
	g := newGame(5)
	if g.level != 5 {
		t.Errorf("hard start level = %d, want 5", g.level)
	}
}

func TestMoveLeft(t *testing.T) {
	g := newGame(0)
	startCol := g.currentCol
	g.moveLeft()
	if g.currentCol != startCol-1 {
		t.Errorf("after moveLeft: col = %d, want %d", g.currentCol, startCol-1)
	}
}

func TestMoveRight(t *testing.T) {
	g := newGame(0)
	startCol := g.currentCol
	g.moveRight()
	if g.currentCol != startCol+1 {
		t.Errorf("after moveRight: col = %d, want %d", g.currentCol, startCol+1)
	}
}

func TestMoveDown(t *testing.T) {
	g := newGame(0)
	startRow := g.currentRow
	moved := g.moveDown()
	if !moved {
		t.Error("moveDown should succeed from starting position")
	}
	if g.currentRow != startRow+1 {
		t.Errorf("after moveDown: row = %d, want %d", g.currentRow, startRow+1)
	}
}

func TestCannotMoveLeftBeyondWall(t *testing.T) {
	g := newGame(0)
	// Move all the way left.
	for range boardCols {
		g.moveLeft()
	}
	col := g.currentCol
	g.moveLeft() // should not move further
	if g.currentCol != col {
		t.Errorf("should not move past left wall: col = %d, was %d", g.currentCol, col)
	}
}

func TestCannotMoveRightBeyondWall(t *testing.T) {
	g := newGame(0)
	// Move all the way right.
	for range boardCols {
		g.moveRight()
	}
	col := g.currentCol
	g.moveRight() // should not move further
	if g.currentCol != col {
		t.Errorf("should not move past right wall: col = %d, was %d", g.currentCol, col)
	}
}

func TestRotate(t *testing.T) {
	g := newGame(0)
	startRot := g.currentRot
	g.rotate()
	// Rotation should change (possibly with wall kick).
	if g.currentRot == startRot {
		// Rotation might legitimately fail in some edge cases, so just check
		// that the game state is valid.
		if !g.canPlace(g.current, g.currentRot, g.currentRow, g.currentCol) {
			t.Error("piece should be in a valid position after rotate attempt")
		}
	}
}

func TestHardDrop(t *testing.T) {
	g := newGame(0)
	startRow := g.currentRow
	dropped := g.hardDrop()
	if dropped == 0 {
		t.Error("hard drop should move piece down at least some rows from top")
	}
	if g.currentRow <= startRow {
		t.Errorf("after hardDrop: row = %d should be > %d", g.currentRow, startRow)
	}
}

func TestGhostRow(t *testing.T) {
	g := newGame(0)
	ghost := g.ghostRow()
	if ghost < g.currentRow {
		t.Errorf("ghost row %d should be >= current row %d", ghost, g.currentRow)
	}
	// Ghost should be at a position where moving down one more is impossible.
	if g.canPlace(g.current, g.currentRot, ghost+1, g.currentCol) {
		t.Error("ghost row should be the lowest valid position")
	}
}

func TestLockPiece(t *testing.T) {
	g := newGame(0)
	g.hardDrop()
	pt := g.current
	row, col, rot := g.currentRow, g.currentCol, g.currentRot
	g.lockPiece()

	// Verify that the piece's cells are now filled.
	shape := pieces[pt][rot]
	for _, off := range shape {
		r, c := row+off[0], col+off[1]
		if !g.board[r][c].filled {
			t.Errorf("cell (%d, %d) should be filled after lockPiece", r, c)
		}
	}
}

func TestClearLines(t *testing.T) {
	g := newGame(0)
	// Fill the bottom row completely.
	for c := range boardCols {
		g.board[boardRows-1][c] = cell{filled: true, piece: pieceI}
	}
	cleared := g.clearLines()
	if cleared != 1 {
		t.Errorf("clearLines() = %d, want 1", cleared)
	}
	// Bottom row should now be empty (shifted from above).
	for c := range boardCols {
		if g.board[boardRows-1][c].filled {
			t.Errorf("bottom row col %d should be empty after clearing", c)
		}
	}
}

func TestClearMultipleLines(t *testing.T) {
	g := newGame(0)
	// Fill the bottom 4 rows.
	for r := boardRows - 4; r < boardRows; r++ {
		for c := range boardCols {
			g.board[r][c] = cell{filled: true, piece: pieceI}
		}
	}
	cleared := g.clearLines()
	if cleared != 4 {
		t.Errorf("clearLines() = %d, want 4", cleared)
	}
}

func TestScoring(t *testing.T) {
	tests := []struct {
		lines int
		level int
		want  int
	}{
		{1, 0, 40},
		{2, 0, 100},
		{3, 0, 300},
		{4, 0, 1200},
		{1, 1, 80},
		{4, 2, 3600},
	}
	for _, tt := range tests {
		g := newGame(tt.level)
		g.addScore(tt.lines)
		if g.score != tt.want {
			t.Errorf("score for %d lines at level %d = %d, want %d", tt.lines, tt.level, g.score, tt.want)
		}
	}
}

func TestLevelUp(t *testing.T) {
	g := newGame(0)
	g.lines = 9
	g.addScore(1) // This should push lines to 10, triggering level 1.
	if g.level != 1 {
		t.Errorf("level = %d, want 1 after 10 lines", g.level)
	}
}

func TestTickInterval(t *testing.T) {
	if got := tickInterval(0); got != 800 {
		t.Errorf("tickInterval(0) = %d, want 800", got)
	}
	if got := tickInterval(5); got != 500 {
		t.Errorf("tickInterval(5) = %d, want 500", got)
	}
	// Floor at 100ms.
	if got := tickInterval(20); got != 100 {
		t.Errorf("tickInterval(20) = %d, want 100", got)
	}
}

func TestFormatScore(t *testing.T) {
	tests := []struct {
		n    int
		want string
	}{
		{0, "0"},
		{100, "100"},
		{1250, "1,250"},
		{1000000, "1,000,000"},
	}
	for _, tt := range tests {
		if got := formatScore(tt.n); got != tt.want {
			t.Errorf("formatScore(%d) = %q, want %q", tt.n, got, tt.want)
		}
	}
}

func TestGameOverScreen(t *testing.T) {
	m, _ := newTestModel(t)
	sendKey(m, "enter") // start game

	// Force game over.
	m.game.gameOver = true
	m.screen = screenGameOver

	view := m.View()
	if !strings.Contains(view, "GAME OVER") {
		t.Error("game over screen should show GAME OVER")
	}
	if !strings.Contains(view, "Score") {
		t.Error("game over screen should show score")
	}
}

func TestRestartFromGameOver(t *testing.T) {
	m, _ := newTestModel(t)
	sendKey(m, "enter") // start game

	m.game.gameOver = true
	m.screen = screenGameOver

	sendKey(m, "r")
	if m.screen != screenGame {
		t.Errorf("expected screenGame after restart, got %d", m.screen)
	}
	if m.game.gameOver {
		t.Error("game should not be over after restart")
	}
}

func TestQuitFromGame(t *testing.T) {
	m, _ := newTestModel(t)
	sendKey(m, "enter") // start game
	sendKey(m, "q")
	if !m.quitting {
		t.Error("should be quitting after pressing q")
	}
}

func TestQuitFromGameOver(t *testing.T) {
	m, _ := newTestModel(t)
	sendKey(m, "enter") // start game
	m.game.gameOver = true
	m.screen = screenGameOver

	sendKey(m, "q")
	if !m.quitting {
		t.Error("should be quitting after pressing q in game over")
	}
}

func TestSoftDropScoring(t *testing.T) {
	m, _ := newTestModel(t)
	sendKey(m, "enter") // start game

	scoreBefore := m.game.score
	sendKey(m, "down")
	if m.game.score != scoreBefore+1 {
		t.Errorf("score after soft drop = %d, want %d", m.game.score, scoreBefore+1)
	}
}

func TestHardDropScoring(t *testing.T) {
	m, _ := newTestModel(t)
	sendKey(m, "enter") // start game

	// Hard drop gives 2 points per row dropped.
	sendKey(m, "space")
	if m.game.score < 2 {
		t.Errorf("score after hard drop = %d, should be at least 2", m.game.score)
	}
}

func TestTickMovesDown(t *testing.T) {
	m, _ := newTestModel(t)
	sendKey(m, "enter") // start game

	rowBefore := m.game.currentRow
	sendTick(m)
	// Piece should either move down by 1, or lock and spawn a new piece at top.
	movedDown := m.game.currentRow == rowBefore+1
	respawned := m.game.currentRow < rowBefore
	if !movedDown && !respawned && !m.game.gameOver {
		t.Errorf("tick should move piece down or lock+respawn: row was %d, now %d", rowBefore, m.game.currentRow)
	}
}

func TestSessionLogs(t *testing.T) {
	m, store := newTestModel(t)

	// Press key to start game — returns a logAction cmd.
	cmd := sendKey(m, "enter")
	if cmd != nil {
		execCmds(cmd)
	}
	time.Sleep(50 * time.Millisecond)

	found := false
	for _, log := range store.SessionLogs {
		if strings.Contains(log.Input, "GAME START") {
			found = true
			break
		}
	}
	if !found {
		t.Error("expected GAME START in session logs")
	}
}

func TestKeypressCounter(t *testing.T) {
	m, _ := newTestModel(t)
	sendKey(m, "enter") // start game
	sendKey(m, "left")
	sendKey(m, "right")
	sendKey(m, "down")

	if m.keypresses != 4 { // enter + 3 game keys
		t.Errorf("keypresses = %d, want 4", m.keypresses)
	}
}

func TestLockDelay(t *testing.T) {
	m, _ := newTestModel(t)
	sendKey(m, "enter") // start game

	// Drop piece to the bottom via ticks until it can't move down.
	for range boardRows + 5 {
		if m.locking {
			break
		}
		sendTick(m)
	}

	if !m.locking {
		t.Fatal("piece should be in locking state after hitting bottom")
	}

	// During lock delay, we should still be able to move left/right.
	colBefore := m.game.currentCol
	sendKey(m, "left")
	if m.game.currentCol >= colBefore {
		// Might not have moved if against wall, try right.
		sendKey(m, "right")
	}

	// Sending a lockMsg should finalize the piece.
	m.Update(lockMsg(time.Now()))
	// After lock, a new piece should have spawned (row near top).
	if m.game.currentRow > 1 && !m.game.gameOver {
		t.Errorf("after lock delay, new piece should spawn near top, got row %d", m.game.currentRow)
	}
}

func TestLockDelayCancelledByDrop(t *testing.T) {
	m, _ := newTestModel(t)
	sendKey(m, "enter") // start game

	// Build a ledge: fill rows 18-19 but leave column 0 empty.
	for r := boardRows - 2; r < boardRows; r++ {
		for c := 1; c < boardCols; c++ {
			m.game.board[r][c] = cell{filled: true, piece: pieceI}
		}
	}

	// Move piece to column 0 area and drop it onto the ledge.
	for range boardCols {
		m.game.moveLeft()
	}
	// Tick down until locking.
	for range boardRows + 5 {
		if m.locking {
			break
		}
		sendTick(m)
	}

	// If piece is on the ledge and we slide it to col 0 (open column),
	// the lock delay should cancel since it can fall further.
	// This test just validates the locking flag logic works.
	if m.locking {
		// Try moving — if piece can drop further, locking should cancel.
		sendKey(m, "left")
		// Whether locking cancels depends on the board state; just verify no crash.
	}
}

func TestSpawnCol(t *testing.T) {
	// All pieces should spawn roughly centered.
	for pt := range pieceType(numPieceTypes) {
		col := spawnCol(pt, 0)
		if col < 0 || col > boardCols-1 {
			t.Errorf("spawnCol(%d, 0) = %d, out of range", pt, col)
		}
		// Verify piece fits at spawn position.
		shape := pieces[pt][0]
		for _, off := range shape {
			c := col + off[1]
			if c < 0 || c >= boardCols {
				t.Errorf("piece %d overflows board at spawn: col+offset = %d", pt, c)
			}
		}
	}
}