"""Canonical serializer + INV-12 round-trip lock (SD-0002 §6.5.5, §6.8)."""
import csv
import io

from app.domains.products import serialize
from app.domains.products.diff import CatalogImage, CatalogProduct, CatalogVariant


def _product(**kw) -> CatalogProduct:
    """A minimal no-option catalog product (one all-NULL variant)."""
    base = dict(
        id=1, handle="moon-mug", title="Moon Mug",
        option_names=(None, None, None),
        fields={
            "title": "Moon Mug", "description_html": None, "vendor": "Acme",
            "product_type": "standalone", "google_product_category": None,
            "tags": [], "status": "active", "published": True,
        },
        variants=[CatalogVariant(
            id=1, options=(None, None, None), position=1,
            fields={"sku": "WG-MUG", "barcode": None, "price": None, "cost": None,
                    "weight": None, "weight_unit": None, "volume": None,
                    "volume_unit": None, "tax_id_1": None, "tax_id_2": None,
                    "inventory_tracker": None, "inventory_qty": None,
                    "variant_image": None})],
        images=[],
    )
    base.update(kw)
    return CatalogProduct(**base)


def _rows(products) -> list[dict]:
    text = "".join(serialize.catalog_to_csv(products))
    return list(csv.DictReader(io.StringIO(text)))


def test_header_is_full_canonical_set():
    text = "".join(serialize.catalog_to_csv([_product()]))
    header = next(csv.reader(io.StringIO(text)))
    # Handle + Title first; every known column present exactly once.
    assert header[0] == "Handle"
    assert "Title" in header and "Variant SKU" in header and "Image Src" in header
    assert len(header) == len(set(header))


def test_single_no_option_product_one_row():
    rows = _rows([_product()])
    assert len(rows) == 1
    assert rows[0]["Handle"] == "moon-mug"
    assert rows[0]["Title"] == "Moon Mug"
    assert rows[0]["Variant SKU"] == "WG-MUG"
    # A no-option product emits no option values.
    assert rows[0]["Option1 Value"] == ""


def _star_tee() -> CatalogProduct:
    """A 3-variant, 2-image product (the sample.csv shape)."""
    return CatalogProduct(
        id=2, handle="star-tee", title="Star Tee",
        option_names=("Size", "Color", None),
        fields={"title": "Star Tee", "description_html": None, "vendor": "Acme",
                "product_type": "standalone", "google_product_category": None,
                "tags": ["apparel", "tees"], "status": "active", "published": True},
        variants=[
            CatalogVariant(id=10, options=("S", "Indigo", None), position=1,
                           fields={"sku": "WG-TEE-S", "variant_image": None}),
            CatalogVariant(id=11, options=("M", "Indigo", None), position=2,
                           fields={"sku": "WG-TEE-M", "variant_image": None}),
            CatalogVariant(id=12, options=("L", "Indigo", None), position=3,
                           fields={"sku": "WG-TEE-L", "variant_image": None}),
        ],
        images=[
            CatalogImage(id=1, source_url="https://x/a.jpg", position=1, alt_text="front"),
            CatalogImage(id=2, source_url="https://x/b.jpg", position=2, alt_text="back"),
        ],
    )


def test_multivariant_with_images_interleaves():
    rows = _rows([_star_tee()])
    assert len(rows) == 3  # max(3 variants, 2 images)
    # Product-level fields only on the first row.
    assert rows[0]["Title"] == "Star Tee" and rows[1]["Title"] == ""
    assert rows[0]["Tags"] == "apparel, tees" and rows[1]["Tags"] == ""
    # Option names on row 0; option values on every variant row.
    assert rows[0]["Option1 Name"] == "Size" and rows[1]["Option1 Name"] == ""
    assert [r["Option1 Value"] for r in rows] == ["S", "M", "L"]
    assert [r["Variant SKU"] for r in rows] == ["WG-TEE-S", "WG-TEE-M", "WG-TEE-L"]
    # Two images on the first two rows; third row has no image.
    assert [r["Image Src"] for r in rows] == ["https://x/a.jpg", "https://x/b.jpg", ""]
    assert [r["Image Position"] for r in rows] == ["1", "2", ""]


def test_more_images_than_variants_emits_image_only_rows():
    p = _product(images=[
        CatalogImage(id=1, source_url="https://x/a.jpg", position=1, alt_text=None),
        CatalogImage(id=2, source_url="https://x/b.jpg", position=2, alt_text=None),
        CatalogImage(id=3, source_url="https://x/c.jpg", position=3, alt_text=None),
    ])
    rows = _rows([p])
    assert len(rows) == 3  # 1 variant, 3 images
    assert rows[0]["Variant SKU"] == "WG-MUG"
    assert rows[1]["Variant SKU"] == "" and rows[1]["Handle"] == "moon-mug"
    assert [r["Image Src"] for r in rows] == ["https://x/a.jpg", "https://x/b.jpg", "https://x/c.jpg"]


def test_fetched_image_serializes_hosted_detail_url():
    product = CatalogProduct(
        id=1, handle="lamp", title="Lamp", option_names=(None, None, None),
        fields={"title": "Lamp", "status": "active"},
        variants=[CatalogVariant(id=1, options=(None, None, None), position=1, fields={})],
        images=[
            CatalogImage(id=55, source_url="https://m.example/a.png", position=1,
                         alt_text=None, status="fetched"),
            CatalogImage(id=56, source_url="https://m.example/b.png", position=2,
                         alt_text=None, status="failed"),
        ],
    )
    rows = list(serialize._product_rows(product, base_url="https://shop.test"))
    srcs = [r.get("Image Src") for r in rows if r.get("Image Src")]
    assert "https://shop.test/api/products/images/55/detail" in srcs  # fetched -> hosted
    assert "https://m.example/b.png" in srcs                          # failed -> source kept


import random

from app.domains.products import codec, diff, validate


def _gen_catalog(seed: int) -> dict:
    """A deterministic random text-field catalog, in load_catalog()'s shape."""
    rng = random.Random(seed)
    words = ["moon", "star", "river", "cloud", "ember", "fern", "slate", "wave"]
    catalog: dict[str, CatalogProduct] = {}
    n_products = rng.randint(1, 6)
    for pid in range(1, n_products + 1):
        handle = "-".join(rng.sample(words, rng.randint(1, 3))) + f"-{pid}"
        if handle in catalog:
            continue
        has_opts = rng.random() < 0.6
        option_names = ("Size", "Color", None) if has_opts else (None, None, None)
        tags = rng.sample(["apparel", "kitchen", "sale", "new"], rng.randint(0, 3))
        fields = {
            "title": f"{handle.title()} Thing",
            "description_html": rng.choice([None, "<p>hi</p>"]),
            "vendor": rng.choice([None, "Acme", "Wiggle Goods"]),
            "product_type": "standalone",
            "google_product_category": rng.choice([None, "Home & Garden"]),
            "tags": tags,
            "status": rng.choice(["draft", "active", "archived"]),
            "published": rng.choice([True, False]),
        }
        variants = []
        if has_opts:
            sizes = rng.sample(["S", "M", "L", "XL"], rng.randint(1, 4))
            for vi, size in enumerate(sizes, start=1):
                # Non-sequential positions (×10) so a serializer that drops the
                # stored position and lets re-import default to file order is
                # caught — a merchant can import explicit positions like 10/20.
                variants.append(CatalogVariant(
                    id=pid * 100 + vi, options=(size, "Indigo", None), position=vi * 10,
                    fields={"sku": f"SKU-{pid}-{vi}", "variant_image": None}))
        else:
            variants.append(CatalogVariant(
                id=pid * 100 + 1, options=(None, None, None), position=rng.choice([1, 5, 9]),
                fields={"sku": f"SKU-{pid}", "variant_image": None}))
        images = []
        for ii in range(rng.randint(0, 3)):
            # Mix fetched and non-fetched images: a fetched image exports its
            # hosted /images/{id}/detail URL, which the diff pre-pass resolves
            # back to the same id -> still a no-op (INV-12 over hosted images).
            status = "fetched" if rng.random() < 0.5 else "pending"
            images.append(CatalogImage(
                id=pid * 10 + ii, source_url=f"https://img/{handle}-{ii}.jpg",
                position=ii + 1, alt_text=rng.choice([None, f"alt {ii}"]),
                status=status))
        catalog[handle] = CatalogProduct(
            id=pid, handle=handle, title=fields["title"], option_names=option_names,
            fields=fields, variants=variants, images=images)
    return catalog


def _roundtrip_diff(catalog: dict, base_url: str = "") -> diff.DiffResult:
    """export → bytes → import pipeline → diff against the same catalog."""
    text = "".join(serialize.catalog_to_csv(catalog.values(), base_url=base_url))
    parsed = codec.parse_csv(text.encode("utf-8"))
    products = validate.build_products(parsed)
    return diff.compute_diff(catalog, products)


def test_inv12_roundtrip_is_noop_over_generated_catalogs():
    for seed in range(200):
        catalog = _gen_catalog(seed)
        # A fixed base_url so fetched images export an absolute hosted URL; the
        # diff resolves it back by id -> the round-trip stays a no-op.
        result = _roundtrip_diff(catalog, base_url="https://shop.test")
        assert result.summary["adds"] == 0, f"seed {seed}: {result.summary}"
        assert result.summary["updates"] == 0, f"seed {seed}: {result.summary}"
        assert result.summary["errors"] == 0, f"seed {seed}: {result.summary}"
        assert result.summary["unchanged"] == len(catalog), f"seed {seed}"


from decimal import Decimal


def test_decimal_and_int_variant_fields_roundtrip():
    catalog = {
        "priced": CatalogProduct(
            id=1, handle="priced", title="Priced",
            option_names=(None, None, None),
            fields={"title": "Priced", "description_html": None, "vendor": None,
                    "product_type": "standalone", "google_product_category": None,
                    "tags": [], "status": "active", "published": True},
            variants=[CatalogVariant(
                id=1, options=(None, None, None), position=1,
                fields={"sku": "P1", "price": Decimal("18.00"),
                        "cost": Decimal("9.5"), "weight": Decimal("0.250"),
                        "inventory_qty": 40, "variant_image": None})],
            images=[],
        )
    }
    result = _roundtrip_diff(catalog)
    assert result.summary["unchanged"] == 1, result.records
    assert result.summary["updates"] == 0


def test_nonsequential_variant_position_roundtrips():
    """A stored variant position that isn't its file order must survive export —
    else re-import reads the empty cell as 'reset to file order' and the round-trip
    spuriously updates (INV-12 regression: position is a CatalogVariant attribute,
    not a fields{} entry, so the serializer must emit it explicitly)."""
    catalog = {
        "tee": CatalogProduct(
            id=1, handle="tee", title="Tee", option_names=("Size", None, None),
            fields={"title": "Tee", "description_html": None, "vendor": None,
                    "product_type": "standalone", "google_product_category": None,
                    "tags": [], "status": "active", "published": True},
            variants=[
                CatalogVariant(id=1, options=("S", None, None), position=10,
                               fields={"sku": "T-S", "variant_image": None}),
                CatalogVariant(id=2, options=("M", None, None), position=20,
                               fields={"sku": "T-M", "variant_image": None}),
            ],
            images=[],
        )
    }
    result = _roundtrip_diff(catalog)
    assert result.summary["unchanged"] == 1, result.records
    assert result.summary["updates"] == 0