"""cev L_plan Planner — design-time LLM that emits a validation_intent_battery.

Spec: docs/build/B5_planner.md + docs/REBUILD_DESIGN.md §2 (decision A, iron-rules
1/2/3, §2.6 layering). Frozen contract: cev/schemas/validation_intent_battery.schema.json.

Core principles carried over from validation_agent/core/planner.py, RESHAPED so the
output is *validation intents only* — no tool_id / no params / no data_construction:
  - dataset-endogenous (iron-rule 1): plan only what feasibility + DataInventory support;
  - the LLM is the decider, ZERO rules (D2): deterministic code only assembles the prompt
    and validates output SHAPE — it never authors intents;
  - intents carry no tool / lib / params / data_construction (iron-rule 2);
  - no silent truncation (D7): everything unsupportable goes to not_planned + reason_code.

This module is intentionally LIGHT: it consumes already-built dicts (edge / paper_context /
feasibility / data_inventory / constraints) + an injected LLM provider, so it imports no
pandas/pyarrow and is unit-testable with a fake provider. Heavy upstream loading lives in
cev/cli.py. HPP runtime never runs this (design-time LLM only; hpp_llm_forbidden guard).
"""
from __future__ import annotations

import json
from pathlib import Path
from typing import Any, Protocol

_SCHEMA_PATH = (
    Path(__file__).resolve().parent.parent / "schemas" / "validation_intent_battery.schema.json"
)

DEFAULT_PLANNER_MODEL = "claude-opus-4-8"
PLANNER_AGENT = "cev_planner"
MAX_PLANNER_SCHEMA_REPAIRS = 2
_MAX_REPAIR_ERRORS = 10

# Mirrored from the frozen schema for convenience (the schema file is the authority).
INTENT_TYPES = (
    "correlation", "main_effect", "subgroup_cate", "dose_response", "mediation_nie_nde",
    "sensitivity", "negative_control", "iv_mr", "bidirectional", "alt_estimator",
)
# tokens that must never appear in an intent (iron-rule 2 purity guard, B5 §3.4)
_FORBIDDEN_TOKENS = ("tool_id", "data_construction", "value_filter", ".tmpl", "data_construction_spec")
_INPUT_LABELS = ("edge", "paper_context", "feasibility", "data_inventory", "constraints")


class PlannerError(RuntimeError):
    """A Planner failure carrying a stable B5 §8 failure code."""

    def __init__(self, message: str, *, code: str) -> None:
        super().__init__(message)
        self.code = code


class LLMProvider(Protocol):  # structural; avoids importing the heavy provider module
    def call(self, *, agent: str, prompt: str, **kwargs: Any) -> dict[str, Any]: ...


PLANNER_SYSTEM_PROMPT = """\
You are the design-time Planner (L_plan) of the cev causal-validation engine. For ONE
causal edge, on the current synthetic dataset (HPP-isomorphic), design the MOST
COMPREHENSIVE, medically-justified validation battery that THE DATA CAN ACTUALLY SUPPORT,
and emit it as VALIDATION INTENTS ONLY.

# YOU ARE THE DECIDER — ZERO RULES, ZERO TOOLS
- Every decision (which mechanisms to probe, which intent_types, which subgroups /
  mediators / contrasts, how comprehensive to be) is YOURS. There is no rule table.
- Do NOT name any tool, tool_id, statistical library, estimator implementation, template,
  or parameter. Do NOT emit data_construction, value_filter, cohort, joins, or per-SD
  scaling — those are decided by downstream layers, not you.
- Express each verification as a validation_intent whose intent_type is from the FIXED enum.

# OUTPUT — STRICT JSON, an object with EXACTLY these three keys and nothing else
{
  "intents": [ validation_intent, ... ],
  "tier_index": { "T1": [int, ...], "T2": [...], ... up to "T7": [...] },
  "not_planned": [ { "intent_type", "x", "y", "reason_code", "detail" }, ... ]
}
No markdown fences, no comments, no trailing commas, no ellipsis, no extra keys. The system
fills edge_id / battery_id / planner_model / dataset_version / feasibility_ref — you OMIT them.
tier_index values are integer indices into intents[]; membership is your decision and a tier
may be absent. Everything you judge warranted but UNSUPPORTABLE goes in not_planned (never
silently skip it).

validation_intent = {
  "intent_type": one of [correlation, main_effect, subgroup_cate, dose_response,
                         mediation_nie_nde, sensitivity, negative_control, iv_mr,
                         bidirectional, alt_estimator],
  "x": <the edge's X concept label>,
  "y": <the edge's Y concept label>,
  "m": <REQUIRED only for mediation_nie_nde — the mediator concept>,
  "subgroup": <REQUIRED only for subgroup_cate — the stratifying concept, e.g. "sex">,
  "contrast_type": <optional: one of level_contrast / unit_increment /
                    category_vs_reference / threshold_above; declare it for a continuous-X
                    main_effect / dose_response / alt_estimator>,
  "covariates": [<concept labels>],
  "rationale": <one sentence of medical justification; NO tool names>
}

# DATASET-ENDOGENOUS (binding — iron-rule 1)
You are given `feasibility` (per-edge runnability + inferred equation/estimator + role
mappings) and `data_inventory` (measured fields, dtypes, cross-table joinability, subgroup
availability, n). Plan ONLY within them — never your imagination.
- An equation / estimator marked not runnable (e.g. instrumental-variable / MR with no
  genetic instrument): do NOT emit a runnable intent for it → not_planned
  (reason_code=equation_not_runnable). EXCEPTION — longitudinal: when
  `feasibility.longitudinal.status == "ok"`, a within-subject change / longitudinal
  dose_response IS runnable (estimator `feasibility.longitudinal.candidate_estimator`,
  e.g. e3_change / e3_lmm over `feasibility.longitudinal.timepoints`) — PLAN it (T5),
  do NOT mark equation_not_runnable.
- A subgroup dimension absent in data_inventory: no subgroup_cate for it → not_planned
  (no_subgroup_support).
- No mediator mapped (edge M empty): no mediation_nie_nde → not_planned (no_mediator_mapped).
- X or Y with mapping status "missing": no runnable intent on that role → not_planned
  (x_not_mapped / y_not_mapped).
- dose_response: a continuous-X shape is valid cross-sectionally; do NOT reflexively skip
  it. `data_inventory[].timepoints` lists the distinct research_stage values on each role
  table — when the X role reports ≥2 timepoints, multi-timepoint X IS available, so PLAN the
  longitudinal / within-subject change dose_response (T5). Reserve not_planned
  (single_timepoint_no_dose) ONLY when the X role table has <2 timepoints.
- Any role resolving to an EXCLUDED, non-physiological source (medications / dietary /
  behavioral or self-reported): never plan it → not_planned (excluded_physiological_only).

# SUBGROUPS ARE DATA-DRIVEN, NOT A FIXED CATALOG
`data_inventory.subgroup_candidates` lists EVERY field across the cohort's tables that can
form ≥2 viable strata (with stratum sizes) — discovered generically from the data, NOT a
preset list. Propose subgroup_cate for ANY candidate that is a clinically plausible effect
modifier of THIS X→Y relationship (e.g. menopausal status for a sex-linked or hormonal
outcome, body-composition / adiposity strata, comorbidity or disease-severity status),
reasoning from clinical knowledge. The legacy `subgroup_availability` (D01–D09) is only a
small subset — do NOT limit yourself to it. Skip a candidate only when it is clinically
implausible as a modifier, or is the exposure/outcome itself.

# COMPREHENSIVENESS — attempt everything the mechanism warrants + label every gap
Cover the tier battery the data supports:
  T1 main_effect (primary X→Y).
  T2 standard subgroups (subgroup_cate per supported effect-modifier; interaction-LRT intent).
  T3 paper-named subgroups (from the study cohort / paper text).
  T4 sensitivity (adjustment-set / robustness variants the data supports).
  T5 dose_response (continuous-X shape; AND when feasibility.longitudinal.status=="ok",
     the within-subject change / longitudinal dose_response over timepoints — plan it).
  T6 alt_estimator (same X→Y under a different estimator family).
  T7 negative_control + bidirectional (reverse Y→X) sanity checks.
  Cross-cutting (not tier-bound): mediation_nie_nde (needs m), correlation (association probe).
"Comprehensive" = attempt everything warranted AND record what the data cannot support in
not_planned — Nature-Medicine level is the target ceiling, not a per-edge guarantee.

# PHYSIOLOGICAL-ONLY
Consume only objective physiological indicators + demographics; never plan an intent whose
role resolves to an excluded source.
"""


def build_planner_input(
    *,
    edge: dict[str, Any],
    paper_context: dict[str, Any],
    feasibility: dict[str, Any],
    data_inventory: dict[str, Any],
    constraints: dict[str, Any],
) -> dict[str, Any]:
    """Assemble the (deterministic, timestamp-free) L_plan prompt input.

    Mirrors the proven validation_agent input shape MINUS data_inspection and
    candidate_subgroups (those came from data_inspector / subgroup_expander, dropped:
    the new planner designs subgroups generically as zero-rule intents).
    """
    return {
        "edge": edge,
        "paper_context": paper_context,
        "feasibility": feasibility,
        "data_inventory": data_inventory,
        "constraints": constraints,
    }


def build_prompt(planner_input: dict[str, Any], *, repair_suffix: str = "") -> str:
    """Render SYSTEM + one <label>\\n{json} block per input key + the output tail.

    Serialization is byte-deterministic (sort_keys=True, no timestamps injected here) so a
    recorded-replay key is stable across runs (mirrors the old planner's determinism note).
    """
    blocks = []
    for label in _INPUT_LABELS:
        body = json.dumps(planner_input.get(label, {}), indent=2, sort_keys=True, ensure_ascii=False)
        blocks.append(f"<{label}>\n{body}")
    user = "\n\n".join(blocks)
    tail = (
        "YOUR OUTPUT (strict JSON object with EXACTLY keys intents, tier_index, "
        "not_planned — nothing else):\n"
    )
    return f"{PLANNER_SYSTEM_PROMPT}\n\nUSER INPUT:\n{user}\n\n{repair_suffix}{tail}"


def _schema_repair_suffix(errors: list[str]) -> str:
    joined = "\n".join(f"- {e}" for e in errors[:_MAX_REPAIR_ERRORS])
    return (
        "PREVIOUS OUTPUT FAILED STRICT SCHEMA VALIDATION. Re-output the FULL JSON object, "
        "fixing EXACTLY these errors and changing nothing else:\n" + joined + "\n\n"
    )


def _load_schema() -> dict[str, Any]:
    return json.loads(_SCHEMA_PATH.read_text(encoding="utf-8"))


def _build_validator():
    """Pick the strictest available validator.

    Their env (jsonschema >= 4.18) uses Draft 2020-12 — the schema's declared dialect.
    Falls back to Draft7 on older jsonschema: the schema's `$ref`s are plain JSON-pointers
    into `$defs`, which Draft7 resolves, and it supports allOf/if-then/patternProperties —
    so validation is equivalent for this contract.
    """
    import jsonschema  # local import: only needed at validation time

    schema = _load_schema()
    draft = getattr(jsonschema, "Draft202012Validator", None) or jsonschema.Draft7Validator
    return draft(schema)


def _schema_errors(battery: dict[str, Any]) -> list[str]:
    validator = _build_validator()
    out: list[str] = []
    for err in sorted(validator.iter_errors(battery), key=lambda e: list(e.path)):
        loc = "/".join(str(p) for p in err.path) or "<root>"
        out.append(f"{loc}: {err.message}")
        if len(out) >= _MAX_REPAIR_ERRORS:
            break
    return out


def _purity_violations(intents: list[dict[str, Any]]) -> list[str]:
    """Iron-rule 2 guard: no tool/data-construction token smuggled into any intent field."""
    bad: list[str] = []
    for idx, intent in enumerate(intents):
        blob = json.dumps(intent, ensure_ascii=False).lower()
        for tok in _FORBIDDEN_TOKENS:
            if tok in blob:
                bad.append(f"intents/{idx}: forbidden token {tok!r} (iron-rule 2: intents carry no tools/data-construction)")
    return bad


def _strip_fences(text: str) -> str:
    t = text.strip()
    if t.startswith("```"):
        t = t.split("\n", 1)[1] if "\n" in t else t[3:]
        if t.rstrip().endswith("```"):
            t = t.rstrip()[:-3]
    return t.strip()


def _extract_content(response: Any) -> dict[str, Any]:
    """Pull the parsed JSON object out of an LLMProvider.call(...) return.

    The production provider returns a dict whose ``response`` key holds the parsed JSON
    (llm_provider.py); recorded/fake providers may hand back the content directly. Tolerant
    of the common shapes so the same planner works in production and in unit tests.
    """
    if isinstance(response, dict):
        if "intents" in response or "not_planned" in response:
            return response
        for key in ("response", "parsed", "content", "output"):
            val = response.get(key)
            if isinstance(val, dict):
                return val
            if isinstance(val, str):
                return json.loads(_strip_fences(val))
        for key in ("text", "raw"):
            val = response.get(key)
            if isinstance(val, str):
                return json.loads(_strip_fences(val))
    if isinstance(response, str):
        return json.loads(_strip_fences(response))
    raise PlannerError(
        f"could not extract a JSON battery object from provider response (type={type(response).__name__}, "
        f"keys={list(response) if isinstance(response, dict) else 'n/a'})",
        code="planner_schema_unrepairable",
    )


class CevPlanner:
    """L_plan: one design-time LLM call (+ bounded schema-repair) → validation_intent_battery.

    The composer owns ONLY the deterministic envelope (battery_id / planner_model /
    dataset_version / feasibility_ref) and SHAPE validation; intents / tier_index /
    not_planned are the LLM's content (never authored by code — B5 §2).
    """

    def __init__(self, provider: LLMProvider, *, mode: str = "m1_v7", planner_model: str = DEFAULT_PLANNER_MODEL) -> None:
        if mode.startswith("hpp"):
            # hpp_llm_forbidden: HPP replays the frozen manifest; it never plans.
            raise PlannerError(
                "the Planner is design-time only; HPP runtime replays a frozen plan with zero LLM",
                code="hpp_llm_forbidden",
            )
        self.provider = provider
        self.mode = mode
        self.planner_model = planner_model

    def compose(
        self,
        *,
        edge_id: str,
        planner_input: dict[str, Any],
        dataset_version: str,
        feasibility_ref: str,
        audit_dir: Path | None = None,
        log: Any = None,
    ) -> dict[str, Any]:
        if not planner_input.get("feasibility"):
            raise PlannerError(
                "Planner requires feasibility input (iron-rule 1: dataset-endogenous)",
                code="planner_missing_feasibility_input",
            )
        _log = log if callable(log) else (lambda _m: None)
        battery_id = f"{edge_id}::planner::{self.planner_model}"
        base_prompt = build_prompt(planner_input)
        errors: list[str] = []

        def _x_role_timepoint_count() -> int | None:
            """Distinct research_stage count of the X role table, read from data_inventory.
            Returns None when X has no mapped dataset or the inventory row lacks timepoints
            (e.g. the static `population` table)."""
            feas = planner_input.get("feasibility") or {}
            inv = planner_input.get("data_inventory") or {}
            x_ds = (feas.get("x_mapping") or {}).get("dataset")
            if not x_ds:
                return None
            bare = str(x_ds).split("-", 1)[-1].split(".", 1)[0]
            for d in inv.get("datasets", []) or []:
                if d.get("dataset") == bare:
                    tps = d.get("timepoints")
                    return len(tps) if isinstance(tps, list) else None
            return None

        def _forbid_false_single_timepoint(bat: dict[str, Any]) -> None:
            """Deterministic guard (backstop for LLM inconsistency): if the X role table has
            ≥2 timepoints, a dose_response recorded as not_planned/single_timepoint_no_dose is
            factually wrong on this dataset — drop that entry so the reason matches the data.
            We never fabricate a planned intent in code (B5 §2: intents are LLM-authored);
            the prompt is responsible for PLANNING the longitudinal dose_response."""
            n = _x_role_timepoint_count()
            if n is None or n < 2:
                return
            nps = bat.get("not_planned")
            if not isinstance(nps, list):
                return
            bat["not_planned"] = [
                it for it in nps
                if not (isinstance(it, dict)
                        and it.get("intent_type") == "dose_response"
                        and it.get("reason_code") == "single_timepoint_no_dose")
            ]

        for attempt in range(MAX_PLANNER_SCHEMA_REPAIRS + 1):
            prompt = base_prompt if not errors else build_prompt(planner_input, repair_suffix=_schema_repair_suffix(errors))
            _log(f"[cev-planner] attempt {attempt + 1}/{MAX_PLANNER_SCHEMA_REPAIRS + 1} (model={self.planner_model})")
            response = self.provider.call(
                agent=PLANNER_AGENT, prompt=prompt, model=self.planner_model, audit_dir=audit_dir,
            )
            content = _extract_content(response)
            battery = {
                "edge_id": edge_id,
                "battery_id": battery_id,
                "planner_model": self.planner_model,
                "dataset_version": dataset_version,
                "feasibility_ref": feasibility_ref,
                "intents": content.get("intents", []),
                "tier_index": content.get("tier_index", {}),
                "not_planned": content.get("not_planned", []),
            }
            _forbid_false_single_timepoint(battery)
            errors = _schema_errors(battery)
            purity = _purity_violations(battery["intents"]) if isinstance(battery["intents"], list) else []
            if purity:
                errors = (errors + purity)[:_MAX_REPAIR_ERRORS]
            if not errors:
                _log(f"[cev-planner] OK: {len(battery['intents'])} intents, "
                     f"{len(battery['not_planned'])} not_planned")
                return battery

        raise PlannerError(
            f"battery failed strict schema/purity after {MAX_PLANNER_SCHEMA_REPAIRS} repairs: {errors}",
            code="planner_schema_unrepairable",
        )