"""C2 compile request construction (``docs/02`` §7.1).

A C2 compile request is sent *independently* to each model. §7.1 fixes what it
carries and — just as importantly — what it hides:

  * **sends** — the *untransformed* image (by content hash; bytes travel
    out-of-band to the model client), the raw question + choices, the source
    structured table / recognized formal candidates when present, the DSL
    grammar, and the ``astNode`` JSON schema the response must match.
  * **hides** — the other model's output, the intended intervention / state, and
    any candidate *transformed* image. The two models must compile from the same
    untouched evidence; neither sees what the other produced or what the
    intervention layer plans to do.

``request_sha256`` is the canonical-JSON hash of the payload, the idempotency key
for response caching and the field recorded on the ``compiled_program`` record.
"""

from __future__ import annotations

from dataclasses import dataclass
from typing import Any

from ..dsl.ast import Dsl
from ..dsl.typecheck import signatures
from ..hashing import canonical_json_hash
from ..sources.base import World

# Fields the request payload is *forbidden* to carry (§7.1 hiding rule). The
# builder asserts none are present so a future caller cannot leak the
# intervention or a sibling model's output into an independent request.
_FORBIDDEN_PAYLOAD_KEYS = frozenset(
    {
        "intended_state",
        "intended_intervention",
        "operator_name",
        "proposer_output",
        "verifier_output",
        "other_model_output",
        "transformed_image_sha256",
        "transformed_image",
        "candidate_transformed_image",
        "original_answer",
    }
)


@dataclass(frozen=True)
class C2Candidate:
    """One C2-eligible item presented to both compilers.

    C2 applies only to ChartQA-H / MMK12 / MMR1-RL / MMMU candidates (§7); the
    assembler (P11) selects them, not the compiler. ``world`` carries the source
    structured table / formal candidates when available (§7.1 "source structured
    table / recognized formal candidates가 있으면 그것"); it may be empty for
    image-only candidates, in which case the models compile from the image alone.
    """

    base_id: str
    dsl: Dsl
    question_sha256: str
    choices_sha256: str
    question_text: str
    choices: tuple[tuple[str, str], ...]  # (key, text) pairs
    image_sha256: str
    world: World


@dataclass(frozen=True)
class CompileRequest:
    """The independent, §7.1-compliant compile request for one model."""

    base_id: str
    dsl: Dsl
    request_sha256: str
    payload: dict[str, Any]
    prompt: str
    image_sha256: str = ""

    def to_dict(self) -> dict[str, Any]:
        return {
            "base_id": self.base_id,
            "dsl": self.dsl,
            "request_sha256": self.request_sha256,
            "image_sha256": self.image_sha256,
            "payload": self.payload,
        }


def _grammar(dsl: Dsl) -> list[dict[str, Any]]:
    """A deterministic, JSON-serializable summary of the DSL operator table."""
    out: list[dict[str, Any]] = []
    for op, sig in sorted(signatures(dsl).items()):
        out.append(
            {
                "op": op,
                "arg_types": list(sig.arg_types),
                "return_type": sig.return_type,
                "commutative": sig.commutative,
                "selector_kind": sig.selector_kind,
                "variadic": sig.variadic,
            }
        )
    return out


def _ast_node_schema_ref() -> dict[str, Any]:
    """A compact pointer to the response schema (the model emits an ``astNode``)."""
    return {
        "$ref": "schemas/compiled_program.schema.json#/$defs/astNode",
        "shape": {
            "op": "string",
            "args": "array of astNode | string | number | boolean",
            "return_type": "string (optional)",
        },
    }


def _world_candidates(world: World) -> dict[str, Any] | None:
    """The structured evidence §7.1 permits sending, pruned to serializable form.

    Only the data-bearing slices a program references are sent (series/points,
    table rows/cells, geometry entities/constraints) — never the rendered image
    bytes, and never any intervention metadata. Returns ``None`` for an empty
    world so image-only candidates carry no ``world_candidates`` key.
    """
    slices: dict[str, Any] = {}
    for key in ("series", "rows", "entities", "constraints"):
        value = world.get(key)
        if value:
            slices[key] = value
    return slices or None


def build_compile_request(candidate: C2Candidate) -> CompileRequest:
    """Assemble the §7.1 independent compile request for ``candidate``.

    The payload carries the DSL, grammar, astNode schema ref, question, choices,
    image content hash, and (when present) the source structured candidates. It
    never carries an intervention, a transformed image, or another model's output.
    """
    candidates = _world_candidates(candidate.world)
    payload: dict[str, Any] = {
        "dsl": candidate.dsl,
        "grammar": _grammar(candidate.dsl),
        "ast_node_schema": _ast_node_schema_ref(),
        "question": candidate.question_text,
        "choices": [{"key": k, "text": t} for k, t in candidate.choices],
        "image_sha256": candidate.image_sha256,
        "base_id": candidate.base_id,
    }
    if candidates is not None:
        payload["world_candidates"] = candidates

    leaked = _FORBIDDEN_PAYLOAD_KEYS & payload.keys()
    if leaked:
        raise AssertionError(f"§7.1 leak in compile request payload: {sorted(leaked)!r}")

    request_sha = canonical_json_hash(payload)
    prompt = _render_prompt(payload)
    return CompileRequest(
        base_id=candidate.base_id,
        dsl=candidate.dsl,
        request_sha256=request_sha,
        payload=payload,
        prompt=prompt,
        image_sha256=candidate.image_sha256,
    )


def _render_prompt(payload: dict[str, Any]) -> str:
    """The natural-language prompt wrapping the JSON payload for the model.

    The model is instructed to emit *only* a JSON object with the program
    envelope subset (``dsl`` / ``program`` / ``referent_selector`` /
    ``required_referent_cardinality``) conforming to ``$defs/astNode``. The
    payload is embedded verbatim; the prompt itself is deterministic and
    hash-stable so ``request_sha256`` (over the payload) is the canonical key.
    """
    grammar = payload["grammar"]
    ops = ", ".join(f"{g['op']}/{g['return_type']}" for g in grammar)
    return (
        "You are an independent program compiler. Compile a single deterministic "
        "question program for the question below using ONLY the given DSL grammar. "
        f"DSL={payload['dsl']}. Operators: {ops}. "
        "Emit ONLY a JSON object: "
        '{"dsl": "<dsl>", "program": <astNode>, '
        '"referent_selector": <astNode|null>, '
        '"required_referent_cardinality": <int|null>}. '
        "An astNode is {op: string, args: [astNode|string|number|boolean], "
        "return_type?: string}. Do not include explanations. "
        f"Payload={_compact_json(payload)}"
    )


def _compact_json(obj: Any) -> str:
    import json

    return json.dumps(obj, sort_keys=True, ensure_ascii=False, separators=(",", ":"))


__all__ = ["C2Candidate", "CompileRequest", "build_compile_request"]