package printer

import (
	"fmt"
	"image"
	"image/color"
	"image/png"
	"os"
	"time"
)

// MockDriver implements PrinterDriver for testing and development.
// Print() saves a PNG to SaveDir (default /tmp) and logs to stdout.
// No hardware required — use this as the default driver until PRT Qutie arrives.
type MockDriver struct {
	connected bool
	// SaveDir is the directory where label PNGs are written.
	// Defaults to /tmp. Override in tests to use t.TempDir().
	SaveDir string
}

// NewMockDriver creates a MockDriver that saves PNGs to /tmp.
func NewMockDriver() *MockDriver {
	return &MockDriver{SaveDir: "/tmp"}
}

// Connect marks the driver as connected.
func (m *MockDriver) Connect() error {
	m.connected = true
	return nil
}

// Disconnect marks the driver as disconnected.
func (m *MockDriver) Disconnect() error {
	m.connected = false
	return nil
}

// Print reconstructs the label image from the 1-bit bitmap and saves it as a PNG.
// Returns ErrEmptyBitmap if bitmap is nil or empty.
func (m *MockDriver) Print(bitmap []byte, width, height int) error {
	if len(bitmap) == 0 {
		return ErrEmptyBitmap
	}

	// Reconstruct image from 1-bit packed bitmap for visual inspection.
	img := image.NewGray(image.Rect(0, 0, width, height))
	rowBytes := (width + 7) / 8
	for y := 0; y < height; y++ {
		for x := 0; x < width; x++ {
			byteIdx := y*rowBytes + x/8
			bit := (bitmap[byteIdx] >> (7 - uint(x%8))) & 1
			if bit == 1 {
				img.SetGray(x, y, color.Gray{Y: 0})
			} else {
				img.SetGray(x, y, color.Gray{Y: 255})
			}
		}
	}

	path := fmt.Sprintf("%s/hwlab-label-%d.png", m.SaveDir, time.Now().UnixMilli())
	f, err := os.Create(path)
	if err != nil {
		return fmt.Errorf("printer: mock create file: %w", err)
	}
	defer f.Close()
	if err := png.Encode(f, img); err != nil {
		return fmt.Errorf("printer: mock encode PNG: %w", err)
	}
	fmt.Printf("[MockDriver] label saved → %s (%dx%d)\n", path, width, height)
	return nil
}