"""Common normalized item schema, content-addressed images, and the eval registry.

Stage 1 of the data pipeline (``docs/02_DATA_PIPELINE.md`` §4) maps every source
row to one immutable :class:`NormalizedItem` matching
``schemas/normalized_item.schema.json``. The canonical ``base_id`` is the
content-addressed hash of ``docs/02`` §3.1 (source identity + question +
choices + image family); ``question_sha256`` / ``choices_sha256`` are over the
exact UTF-8 source bytes (the model input string is never normalized). Images
are content-addressed by their SHA-256 so the same bytes are stored once and
referenced by hash from any mount.

Stage 0 (``docs/02`` §3) freezes the evaluation registry
(``evaluation_items.v1.jsonl``) *before* any training source is touched. The
registry is write-once: a second freeze that would change its bytes is a hard
failure, never a silent overwrite.
"""

from __future__ import annotations

from collections.abc import Callable, Iterable, Iterator, Mapping, Sequence
from dataclasses import dataclass
from pathlib import Path
from typing import Any, Literal

from ..atomic_io import JsonlAppender, atomic_write_bytes, atomic_write_jsonl, read_jsonl
from ..hashing import (
    base_id as compute_base_id,
)
from ..hashing import (
    canonical_json,
    choices_sha256,
    sha256_bytes,
)
from ..hashing import (
    image_family_sha256 as compute_image_family_sha256,
)
from ..hashing import question_sha256 as compute_question_sha256
from ..paths import repo_root
from ..schema_io import load_schema, validate

SCHEMA_VERSION = 2

AnswerType = Literal["multiple_choice", "integer", "number", "expression", "short_text", "boolean"]
# ADR-0002 normalized-item policies (schemas/normalized_item.schema.json v2).
# C1 rows come from source-native structured worlds (PlotQA, Geometry3K); C2 rows
# are dual-compiled train candidates; untouched rows are retention-eval only;
# blocked rows are held back and never substituted.
Policy = Literal[
    "c1_train_candidate",
    "c1_certified_eval_candidate",
    "c2_train_candidate",
    "untouched_evaluation_only",
    "blocked",
]

# A resolver turns one native image reference (a path/relative name in the raw
# row) into its raw bytes. The importer never opens files itself, so importers
# are unit-testable with an in-memory resolver.
ImageResolver = Callable[[str], bytes]

_NORMALIZED_ITEM_SCHEMA: dict[str, Any] | None = None


class IngestError(ValueError):
    """Raised when a source row violates an ingest invariant.

    Invariants are hard failures (never silently dropped): a non-math MMK12 row
    is source revision drift, not a row to skip.
    """


class RegistryFrozenError(IngestError):
    """Raised when a write-once registry would be changed by a re-freeze."""


def normalized_item_schema() -> dict[str, Any]:
    """Load and cache the compiled ``normalized_item`` JSON Schema."""
    global _NORMALIZED_ITEM_SCHEMA
    if _NORMALIZED_ITEM_SCHEMA is None:
        _NORMALIZED_ITEM_SCHEMA = load_schema(
            repo_root() / "schemas" / "normalized_item.schema.json"
        )
    return _NORMALIZED_ITEM_SCHEMA


def validate_normalized_item(row: Mapping[str, Any]) -> None:
    """Raise :class:`IngestError` if ``row`` violates the normalized item schema."""
    errors = validate(dict(row), normalized_item_schema())
    if errors:
        raise IngestError("normalized item failed schema validation: " + "; ".join(errors))


# --- content-addressed image store -----------------------------------------


def _ext_for(data: bytes) -> str:
    """Infer a file extension from image bytes (PNG/JPEG), else ``bin``."""
    if data.startswith(b"\x89PNG\r\n\x1a\n"):
        return "png"
    if data.startswith(b"\xff\xd8\xff"):
        return "jpg"
    return "bin"


@dataclass
class ImageStore:
    """Store image bytes content-addressed under ``<output>/images/<sha>.<ext>``.

    The same bytes are written once; repeat stores are a no-op. Paths are
    returned relative to ``base_dir`` so artifacts reproduce across mounts.
    """

    base_dir: Path

    def __post_init__(self) -> None:
        (self.base_dir / "images").mkdir(parents=True, exist_ok=True)

    def store(self, data: bytes) -> tuple[str, str]:
        """Store ``data``; return ``(relative_path, sha256)``."""
        digest = sha256_bytes(data)
        ext = _ext_for(data)
        relative = f"images/{digest}.{ext}"
        target = self.base_dir / relative
        if not target.exists():
            atomic_write_bytes(target, data)
        return relative, digest


class DirectoryImageResolver:
    """Resolve native image refs to bytes by reading from a root directory."""

    def __init__(self, root: str | Path) -> None:
        self.root = Path(root)

    def __call__(self, ref: str) -> bytes:
        return (self.root / ref).read_bytes()


# --- normalized item -------------------------------------------------------


@dataclass(frozen=True)
class Choice:
    """One multiple-choice option in source order."""

    key: str
    text: str

    def to_dict(self) -> dict[str, str]:
        return {"key": self.key, "text": self.text}


@dataclass(frozen=True)
class NormalizedItem:
    """One immutable normalized source row (``docs/02`` §4 schema)."""

    base_id: str
    source: str
    source_revision: str
    source_config: str
    source_split: str
    source_native_id: str
    question: str
    question_sha256: str
    choices: tuple[Choice, ...]
    choices_sha256: str
    answer_raw: str | int | bool
    answer_canonical: str | int | bool
    answer_type: AnswerType
    image_paths: tuple[str, ...]
    image_sha256: tuple[str, ...]
    policy: Policy
    provenance: dict[str, Any]
    subject: str | None = None
    license_gate: str | None = None

    def to_row(self) -> dict[str, Any]:
        """Serialize to the schema-conforming dict written to ``items.jsonl``."""
        row: dict[str, Any] = {
            "schema_version": SCHEMA_VERSION,
            "base_id": self.base_id,
            "source": self.source,
            "source_revision": self.source_revision,
            "source_config": self.source_config,
            "source_split": self.source_split,
            "source_native_id": self.source_native_id,
            "question": self.question,
            "question_sha256": self.question_sha256,
            "choices": [c.to_dict() for c in self.choices],
            "choices_sha256": self.choices_sha256,
            "answer_raw": self.answer_raw,
            "answer_canonical": self.answer_canonical,
            "answer_type": self.answer_type,
            "image_paths": list(self.image_paths),
            "image_sha256": list(self.image_sha256),
            "provenance": dict(self.provenance),
            "policy": self.policy,
        }
        if self.subject is not None:
            row["subject"] = self.subject
        if self.license_gate is not None:
            row["license_gate"] = self.license_gate
        return row


def _native_row_sha256(row: Mapping[str, Any]) -> str:
    """SHA-256 of the native row's canonical JSON (the source-record fingerprint)."""
    return sha256_bytes(canonical_json(dict(row)).encode("utf-8"))


def canonicalize_mc_answer(answer: str, choices: Sequence[Choice]) -> str | int | bool:
    """Map a multiple-choice answer to its choice key when it matches a text.

    Sources disagree on whether the answer is a key (``"B"``) or the option
    text (``"42"``). The canonical form is the choice key when the raw answer
    equals one option's text; otherwise the raw string is preserved.
    """
    text_answer = str(answer).strip()
    for choice in choices:
        if text_answer == str(choice.text).strip():
            return choice.key
    return text_answer


def make_item(
    *,
    source: str,
    source_revision: str,
    source_config: str,
    source_split: str,
    source_native_id: str,
    question: str,
    choices: Sequence[Choice] | Sequence[Mapping[str, str]],
    answer_raw: str | int | bool,
    answer_canonical: str | int | bool,
    answer_type: AnswerType,
    image_paths: Sequence[str],
    image_sha256: Sequence[str],
    policy: Policy,
    native_row: Mapping[str, Any],
    subject: str | None = None,
    license_gate: str | None = None,
    extra_provenance: Mapping[str, Any] | None = None,
) -> NormalizedItem:
    """Build a :class:`NormalizedItem`, computing ``base_id`` and byte hashes.

    ``base_id`` is the content-addressed hash of ``docs/02`` §3.1 —
    sha256(canonical_json({source, source_revision, source_native_id,
    image_family_sha256, question_sha256, choices_sha256})). ``source_config``
    and ``source_split`` are stored on the item but excluded from the ID. The
    native row's canonical-JSON SHA-256 is recorded in provenance so a row can
    be traced back to its source record.
    """
    if not question:
        raise IngestError(f"{source}: question must be non-empty")
    if not image_paths or len(image_paths) != len(image_sha256):
        raise IngestError(
            f"{source}/{source_native_id}: image_paths and image_sha256 must be "
            "parallel non-empty sequences"
        )
    norm_choices = tuple(
        c if isinstance(c, Choice) else Choice(key=str(c["key"]), text=str(c["text"]))
        for c in choices
    )
    q_sha = compute_question_sha256(question)
    c_sha = choices_sha256([{"key": c.key, "text": c.text} for c in norm_choices])
    fam_sha = compute_image_family_sha256(image_sha256)
    bid = compute_base_id(
        source=source,
        source_revision=source_revision,
        source_native_id=source_native_id,
        image_family_sha256=fam_sha,
        question_sha256=q_sha,
        choices_sha256=c_sha,
    )
    provenance: dict[str, Any] = {
        "native_row_json_sha256": _native_row_sha256(native_row),
    }
    if extra_provenance:
        provenance.update(extra_provenance)
    item = NormalizedItem(
        base_id=bid,
        source=source,
        source_revision=source_revision,
        source_config=source_config,
        source_split=source_split,
        source_native_id=str(source_native_id),
        question=question,
        question_sha256=q_sha,
        choices=norm_choices,
        choices_sha256=c_sha,
        answer_raw=answer_raw,
        answer_canonical=answer_canonical,
        answer_type=answer_type,
        image_paths=tuple(image_paths),
        image_sha256=tuple(image_sha256),
        policy=policy,
        provenance=provenance,
        subject=subject,
        license_gate=license_gate,
    )
    validate_normalized_item(item.to_row())
    return item


# --- ingest driver ---------------------------------------------------------


@dataclass
class IngestResult:
    """Summary of one ingest run."""

    source: str
    split: str
    written: int
    dropped: int
    output_path: Path

    @property
    def ok(self) -> bool:
        return self.written > 0 or self.dropped > 0


def write_items(
    output_path: str | Path,
    items: Iterable[NormalizedItem],
    *,
    fsync: bool = True,
) -> int:
    """Atomically write ``items`` as canonical JSONL; return the row count."""
    rows = [item.to_row() for item in items]
    atomic_write_jsonl(output_path, rows, fsync_dir=fsync)
    return len(rows)


def append_items(output_path: str | Path, items: Iterable[NormalizedItem]) -> int:
    """Append items to an existing JSONL with per-record fsync (resume-friendly)."""
    count = 0
    with JsonlAppender(output_path) as appender:
        for item in items:
            appender.append(item.to_row())
            count += 1
    return count


def read_items(path: str | Path) -> Iterator[dict[str, Any]]:
    """Yield parsed normalized-item rows from ``path``."""
    yield from read_jsonl(path)


# --- evaluation registry ---------------------------------------------------


def registry_row(item: NormalizedItem) -> dict[str, Any]:
    """Build one ``evaluation_items.v1.jsonl`` row from a normalized item.

    Fingerprint fields (``image_phash``, ``ocr_minhash_ref``,
    ``question_minhash_ref``) are left ``None`` here and populated by the P3
    ``fingerprint`` stage; the identity + content fields are frozen now.
    """
    return {
        "base_id": item.base_id,
        "source": item.source,
        "source_revision": item.source_revision,
        "config": item.source_config,
        "split": item.source_split,
        "native_id": item.source_native_id,
        "question_sha256": item.question_sha256,
        "choices_sha256": item.choices_sha256,
        "image_sha256": list(item.image_sha256),
        "image_phash": None,
        "ocr_minhash_ref": None,
        "question_minhash_ref": None,
        "policy": item.policy,
    }


def text_registry_row(
    *,
    source: str,
    source_revision: str,
    config: str,
    split: str,
    native_id: str,
    question: str,
    choices: Sequence[Choice] | Sequence[Mapping[str, str]],
    answer_canonical: str | int | bool,
    policy: Policy = "untouched_evaluation_only",
) -> dict[str, Any]:
    """Build a registry row for a text-only eval item (no image, e.g. MMLU-Pro).

    Text-only ``untouched`` probes are retention checks, not intervention
    candidates, so they carry no image fingerprints. They are recorded directly
    in the registry rather than as visual :class:`NormalizedItem` rows.
    """
    norm_choices = tuple(
        c if isinstance(c, Choice) else Choice(key=str(c["key"]), text=str(c["text"]))
        for c in choices
    )
    q_sha = compute_question_sha256(question)
    c_sha = choices_sha256([{"key": c.key, "text": c.text} for c in norm_choices])
    # Text-only probes carry no images: their image family is the empty set.
    fam_sha = compute_image_family_sha256([])
    return {
        "base_id": compute_base_id(
            source=source,
            source_revision=source_revision,
            source_native_id=native_id,
            image_family_sha256=fam_sha,
            question_sha256=q_sha,
            choices_sha256=c_sha,
        ),
        "source": source,
        "source_revision": source_revision,
        "config": config,
        "split": split,
        "native_id": str(native_id),
        "question_sha256": q_sha,
        "choices_sha256": c_sha,
        "image_sha256": [],
        "image_phash": None,
        "ocr_minhash_ref": None,
        "question_minhash_ref": None,
        "policy": policy,
        "answer_canonical": answer_canonical,
    }


@dataclass(frozen=True)
class FrozenRegistry:
    """A write-once evaluation registry on disk."""

    path: Path
    sha256: str
    row_count: int


def _registry_rows_keyed(rows: Iterable[Mapping[str, Any]]) -> dict[str, dict[str, Any]]:
    return {str(r["base_id"]): dict(r) for r in rows}


def freeze_registry(
    output_path: str | Path,
    rows: Sequence[Mapping[str, Any]],
    *,
    force: bool = False,
    resume: bool = False,
) -> FrozenRegistry:
    """Write the evaluation registry write-once; return its hash and row count.

    If the registry already exists:
      - ``force`` overwrites it atomically.
      - ``resume`` succeeds only if the existing rows are byte-identical to the
        computed rows (idempotent re-freeze); a mismatch raises
        :class:`RegistryFrozenError`.
      - otherwise the existing file is left untouched and a
        :class:`RegistryFrozenError` is raised.
    """
    path = Path(output_path)
    path.parent.mkdir(parents=True, exist_ok=True)
    if path.exists():
        if not force and not resume:
            raise RegistryFrozenError(
                f"evaluation registry already frozen at {path}; "
                "use --force to overwrite or --resume to verify"
            )
        if resume:
            existing = _registry_rows_keyed(read_jsonl(path))
            computed = _registry_rows_keyed(rows)
            if existing != computed:
                raise RegistryFrozenError(
                    f"evaluation registry at {path} differs from the computed "
                    "freeze; refusing to overwrite a frozen registry"
                )
            return _hash_registry(path)
    atomic_write_jsonl(path, rows)
    return _hash_registry(path)


def _hash_registry(path: str | Path) -> FrozenRegistry:
    from ..hashing import sha256_file

    rows = list(read_jsonl(path))
    return FrozenRegistry(path=Path(path), sha256=sha256_file(path), row_count=len(rows))


# --- helpers shared by importers -------------------------------------------


def infer_open_answer_type(answer: str) -> AnswerType:
    """Classify an open-ended answer string as integer/number/short_text."""
    text = str(answer).strip()
    if text.lstrip("-+").isdigit():
        return "integer"
    try:
        float(text)
    except ValueError:
        return "short_text"
    return "number"


def mc_choices(texts: Sequence[str], *, keys: Sequence[str] | None = None) -> list[Choice]:
    """Build lettered choices (A, B, C, ...) from option texts in source order."""
    if keys is None:
        keys = [chr(ord("A") + i) for i in range(len(texts))]
    if len(keys) != len(texts):
        raise IngestError(f"choices/keys length mismatch: {len(keys)} keys vs {len(texts)} texts")
    return [Choice(key=k, text=str(t)) for k, t in zip(keys, texts, strict=True)]