"""Tests for hokusai.image format detection and conversion."""

from __future__ import annotations

from pathlib import Path

from PIL import Image

from hokusai.image import api_format_for_extension, ensure_image_format


class TestApiFormatForExtension:
    """Tests for mapping extensions to API format strings."""

    def test_png(self) -> None:
        assert api_format_for_extension(".png") == "png"

    def test_jpg(self) -> None:
        assert api_format_for_extension(".jpg") == "jpeg"

    def test_jpeg(self) -> None:
        assert api_format_for_extension(".jpeg") == "jpeg"

    def test_webp(self) -> None:
        assert api_format_for_extension(".webp") == "webp"

    def test_txt_returns_none(self) -> None:
        assert api_format_for_extension(".txt") is None

    def test_case_insensitive(self) -> None:
        assert api_format_for_extension(".PNG") == "png"


class TestEnsureImageFormat:
    """Tests for in-place image format conversion."""

    def test_png_file_with_png_extension_unchanged(self, tmp_path: Path) -> None:
        path = tmp_path / "img.png"
        img = Image.new("RGB", (10, 10), color="red")
        img.save(path, format="PNG")
        original_bytes = path.read_bytes()

        ensure_image_format(path)

        assert path.read_bytes() == original_bytes

    def test_jpeg_file_with_jpg_extension_unchanged(self, tmp_path: Path) -> None:
        path = tmp_path / "img.jpg"
        img = Image.new("RGB", (10, 10), color="red")
        img.save(path, format="JPEG")
        original_bytes = path.read_bytes()

        ensure_image_format(path)

        assert path.read_bytes() == original_bytes

    def test_png_file_converted_to_jpg(self, tmp_path: Path) -> None:
        path = tmp_path / "img.jpg"
        img = Image.new("RGB", (10, 10), color="red")
        img.save(path, format="PNG")

        with Image.open(path) as check:
            assert check.format == "PNG"

        ensure_image_format(path)

        with Image.open(path) as check:
            assert check.format == "JPEG"

    def test_jpeg_file_converted_to_png(self, tmp_path: Path) -> None:
        path = tmp_path / "img.png"
        img = Image.new("RGB", (10, 10), color="red")
        img.save(path, format="JPEG")

        with Image.open(path) as check:
            assert check.format == "JPEG"

        ensure_image_format(path)

        with Image.open(path) as check:
            assert check.format == "PNG"

    def test_png_file_converted_to_webp(self, tmp_path: Path) -> None:
        path = tmp_path / "img.webp"
        img = Image.new("RGB", (10, 10), color="red")
        img.save(path, format="PNG")

        ensure_image_format(path)

        with Image.open(path) as check:
            assert check.format == "WEBP"

    def test_rgba_png_converted_to_jpg_flattened(self, tmp_path: Path) -> None:
        path = tmp_path / "img.jpg"
        img = Image.new("RGBA", (10, 10), color=(255, 0, 0, 128))
        img.save(path, format="PNG")

        ensure_image_format(path)

        with Image.open(path) as check:
            assert check.format == "JPEG"
            assert check.mode == "RGB"

    def test_text_extension_ignored(self, tmp_path: Path) -> None:
        path = tmp_path / "file.txt"
        _ = path.write_text("hello")
        original = path.read_bytes()

        ensure_image_format(path)

        assert path.read_bytes() == original

    def test_jpeg_extension_alias(self, tmp_path: Path) -> None:
        path = tmp_path / "img.jpeg"
        img = Image.new("RGB", (10, 10), color="red")
        img.save(path, format="PNG")

        ensure_image_format(path)

        with Image.open(path) as check:
            assert check.format == "JPEG"