package canvas

import (
	"database/sql"
	"path/filepath"
	"testing"

	"penguins.lan/database"
)

func canvasTestDB(t *testing.T) *sql.DB {
	db, err := sql.Open("sqlite3", filepath.Join(t.TempDir(), "c.db"))
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { db.Close() })
	if _, err := database.Migrate(db); err != nil {
		t.Fatal(err)
	}
	return db
}

func pixelAt(buf []byte, x, y int) int {
	i := (y*Cols + x) * 3
	return int(buf[i])<<16 | int(buf[i+1])<<8 | int(buf[i+2])
}

func TestCurrentCanvasReplaysPixels(t *testing.T) {
	db := canvasTestDB(t)

	if _, err := database.SavePixel(db, "u", 1, 2, 0xe50000); err != nil {
		t.Fatal(err)
	}

	buf, err := currentCanvas(db)
	if err != nil {
		t.Fatal(err)
	}
	if got := pixelAt(buf, 1, 2); got != 0xe50000 {
		t.Errorf("placed pixel = %06x, want e50000", got)
	}
	if got := pixelAt(buf, 0, 0); got != defaultColor {
		t.Errorf("untouched pixel = %06x, want white", got)
	}
}

func TestSnapshotBakesThenReplays(t *testing.T) {
	db := canvasTestDB(t)

	if _, err := database.SavePixel(db, "u", 5, 5, 0x000000); err != nil {
		t.Fatal(err)
	}
	if err := takeSnapshot(db); err != nil {
		t.Fatal(err)
	}
	// a placement after the snapshot must be replayed on top of it
	if _, err := database.SavePixel(db, "u", 6, 6, 0x02be01); err != nil {
		t.Fatal(err)
	}

	buf, err := currentCanvas(db)
	if err != nil {
		t.Fatal(err)
	}
	if got := pixelAt(buf, 5, 5); got != 0x000000 {
		t.Errorf("baked pixel = %06x, want black", got)
	}
	if got := pixelAt(buf, 6, 6); got != 0x02be01 {
		t.Errorf("replayed pixel = %06x, want green", got)
	}

	// snapshots are kept to one row
	if err := takeSnapshot(db); err != nil {
		t.Fatal(err)
	}
	var n int
	if err := db.QueryRow("SELECT COUNT(*) FROM canvas_snapshots").Scan(&n); err != nil {
		t.Fatal(err)
	}
	if n != 1 {
		t.Errorf("snapshot rows = %d, want 1", n)
	}
}