"""IMP-33 u3 — AI fallback prompt builder (fallback path only).

System+user prompt for the Anthropic client (u4). MDX is READ-ONLY
(`feedback_ai_isolation_contract`); output is constrained to the u2
schema; frame_id swap is forbidden (V4 rank-1 protected,
`feedback_phase_z_spacing_direction`). Inputs per Stage 2 plan: V4
result (route=ai_adaptation_required, cardinality), frame_contract,
frame_visual HTML, figma_to_html_agent partial JSON, Internal Region,
MDX text.
"""
from __future__ import annotations

import json
from typing import Any

from src.phase_z2_ai_fallback.schema import FORBIDDEN_KINDS, ProposalKind

V4_ROUTE_AI_ADAPTATION = "ai_adaptation_required"

_ALLOWED_KINDS = ", ".join(sorted(k.value for k in ProposalKind))
_FORBIDDEN_KINDS = ", ".join(sorted(FORBIDDEN_KINDS))

SYSTEM_PROMPT = (
    "You are an IMP-33 AI fallback adapter for Phase Z slide composition.\n"
    "STRICT RULES:\n"
    "  1. MDX text in the user payload is READ-ONLY. Do NOT rewrite, "
    "compress, or paraphrase MDX.\n"
    "  2. Output MUST be a single JSON object conforming to AiFallbackProposal.\n"
    f"  3. proposal_kind MUST be one of: {_ALLOWED_KINDS}.\n"
    f"  4. Do NOT propose any of: {_FORBIDDEN_KINDS}.\n"
    "  5. Do NOT change frame_id — V4 rank-1 frame is locked.\n"
    "  6. Preferred Task-12 output is proposal_kind='design_adaptation_plan': "
    "plan frame/layout/repeat changes only; do NOT output final text slots.\n"
    "  7. Do NOT create titles, labels, summaries, body text, or slot content. "
    "The code layer will place MDX verbatim text.\n"
    "  8. Keep declared frame slots (text/table/image/details) accounted for.\n"
    "  9. Respect Internal Region containment; place content units within "
    "the declared region only."
)


def build_ai_fallback_prompt(
    *,
    v4_result: dict[str, Any],
    frame_contract: dict[str, Any],
    frame_visual_html: str,
    figma_partial_json: dict[str, Any],
    internal_region: dict[str, Any],
    mdx_text: str,
) -> dict[str, str]:
    """Build system+user prompt strings for the fallback AI adapter.

    Raises:
        ValueError: when ``v4_result.route`` is not
            ``ai_adaptation_required`` — the fallback prompt MUST NOT be
            built outside this route (normal-path AI call count must
            remain 0; PZ-1).
    """
    route = v4_result.get("route") or v4_result.get("imp05_route_hint")
    if route != V4_ROUTE_AI_ADAPTATION:
        raise ValueError(
            f"build_ai_fallback_prompt: v4_result.route={route!r} is not "
            f"{V4_ROUTE_AI_ADAPTATION!r}; fallback prompt MUST NOT be built "
            "outside the AI adaptation route."
        )
    user_payload = {
        "v4": {
            "route": route,
            "cardinality": v4_result.get("cardinality")
            or v4_result.get("cardinality_signature"),
            "label": v4_result.get("label"),
            "frame_id": v4_result.get("frame_id"),
            "rank": v4_result.get("rank"),
        },
        "frame_contract": frame_contract,
        "frame_visual_html": frame_visual_html,
        "figma_partial_json": figma_partial_json,
        "internal_region": internal_region,
        "mdx_text_READ_ONLY": mdx_text,
        "task12_output_contract": {
            "preferred_proposal_kind": ProposalKind.DESIGN_ADAPTATION_PLAN.value,
            "allowed_operation_examples": [
                "increase_repeat_count",
                "split_group_across_repeat_blocks",
                "rebalance_zone_ratio",
                "compact_spacing",
                "use_repeatable_frame",
            ],
            "forbidden_content_fields": [
                "text",
                "title",
                "label",
                "body",
                "slots",
                "mdx_text",
                "summary",
                "raw_html",
                "raw_css",
            ],
        },
    }
    return {
        "system": SYSTEM_PROMPT,
        "user": json.dumps(user_payload, ensure_ascii=False),
    }