"""Planner node — Plane-2 pipeline PLAN stage (design §3.3, §7.1 P2).

The planner turns the clarified task context into a **phased plan** (the format
these design docs use) by calling Claude through the billing seam, then hands
the plan to the adversarial review loop.

Pipeline position (§3.3)::

    INTAKE -> CLARIFIER -> [PLANNER] -> REVIEW LOOP -> BUILDERS -> VERIFIERS

Responsibilities of this leaf (Phase P2, §7.1):

* Read the clarified context out of :class:`~agent_team.task_model.PipelineState`
  (the task description + the full clarifier Q&A history).
* On a **review loop-back** (§3.3 "Loops back to the planner on REQUEST
  CHANGES"), fold the prior ``review_verdicts`` into the re-plan prompt so the
  next plan answers the reviewer's objections.
* Call :func:`agent_team.billing.claude_invoke` to draft the plan, then parse
  the model's reply into a structured ``plan`` dict.
* Return a **partial** ``PipelineState`` update advancing the phase to
  :attr:`~agent_team.task_model.Phase.REVIEW`.
* Enforce the convergence bound (§3.3 "escalates to Adam if it cannot
  converge"): after :data:`MAX_PLAN_REVISIONS` REQUEST-CHANGES loop-backs the
  task is parked + ALARM-ed rather than spun (status ``PARKED``, phase
  ``PARKED``).

This module imports the committed foundation contracts verbatim
(:mod:`agent_team.task_model`, :mod:`agent_team.billing`) and does no I/O of its
own beyond the injected Claude seam — keeping the node a pure LangGraph
state-transition function that is trivially unit-testable.
"""

from __future__ import annotations

import json
import re
from collections.abc import Callable
from typing import Any

from agent_team.billing import ClaudeResult, claude_invoke
from agent_team.task_model import Phase, PipelineState, TaskStatus

# Optional context-provider callable (WS5): () -> str. When injected, its
# result is prepended to the planner prompt. Default None = unchanged behavior.
ContextProvider = Callable[[], str]

__all__ = [
    "MAX_PLAN_REVISIONS",
    "PlannerError",
    "build_plan_prompt",
    "parse_plan",
    "plan_node",
]

# §3.3 / §6.6 — the planner must converge or park. After this many
# REQUEST-CHANGES loop-backs from the review stage the task is escalated to
# Adam (parked + ALARM) instead of looping forever.
MAX_PLAN_REVISIONS = 3

# The reviewer verdict string that sends a plan back to the planner. Kept here
# (rather than imported from a review node that does not exist yet) so this leaf
# stays self-contained; the review leaf will emit this same token.
_REQUEST_CHANGES = "REQUEST_CHANGES"


class PlannerError(Exception):
    """Raised when the planner cannot produce a usable plan.

    Distinct from a *converged-but-rejected* plan (which loops back through
    review) — this signals the planner itself failed (empty/garbled model
    output), so the coordinator can fail the task rather than advance it.
    """


def _task_description(state: PipelineState) -> str:
    """Pull the task description out of the graph state.

    Intake writes the originating ask; we look in the conventional places and
    fall back to an empty string so a malformed state surfaces as an empty
    prompt section rather than a ``KeyError`` inside the node.
    """
    plan = state.get("plan") or {}
    if isinstance(plan, dict):
        desc = plan.get("task") or plan.get("description")
        if isinstance(desc, str) and desc.strip():
            return desc.strip()
    desc = state.get("task")  # type: ignore[call-overload]
    if isinstance(desc, str) and desc.strip():
        return desc.strip()
    return ""


def _format_qa_history(qa_history: list[Any]) -> str:
    """Render the clarifier Q&A history into prompt text.

    Each entry may be a ``{"question": ..., "answer": ...}`` mapping (the
    clarifier's shape) or a plain string; both are handled so the planner does
    not couple tightly to the clarifier's internal record format.
    """
    lines: list[str] = []
    for idx, entry in enumerate(qa_history, start=1):
        if isinstance(entry, dict):
            question = str(entry.get("question", "")).strip()
            answer = str(entry.get("answer", "")).strip()
            if question or answer:
                lines.append(f"{idx}. Q: {question}\n   A: {answer}")
        else:
            text = str(entry).strip()
            if text:
                lines.append(f"{idx}. {text}")
    return "\n".join(lines)


def _format_review_feedback(review_verdicts: list[Any]) -> str:
    """Render prior review verdicts into re-plan guidance (§3.3 loop-back).

    Only the most recent verdict drives the re-plan, but earlier ones are
    summarised so the planner does not re-introduce already-rejected ideas.
    """
    if not review_verdicts:
        return ""
    lines: list[str] = []
    for idx, verdict in enumerate(review_verdicts, start=1):
        if isinstance(verdict, dict):
            # The review stage (review_loop.ReviewResult.to_dict) writes the keys
            # "verdict" (decision) and "findings" (the reviewer's objections).
            # Read those FIRST — the old "decision"/"notes"/"comment" keys never
            # existed on a real verdict, so the planner re-planned with EMPTY
            # feedback and kept re-introducing the rejected flaw ("assumptions
            # persist" → cap → park). Old keys kept as fallbacks for safety.
            decision = str(
                verdict.get("verdict") or verdict.get("decision") or ""
            ).strip()
            notes = str(
                verdict.get("findings")
                or verdict.get("notes")
                or verdict.get("comment")
                or ""
            ).strip()
            lines.append(f"Review {idx} [{decision}]: {notes}".rstrip())
        else:
            lines.append(f"Review {idx}: {str(verdict).strip()}")
    return "\n".join(lines)


def build_plan_prompt(
    state: PipelineState, *, context_provider: ContextProvider | None = None
) -> str:
    """Build the Claude prompt that drafts (or re-drafts) the phased plan.

    Pure string assembly over the graph state — no I/O — so the prompt shape is
    directly unit-testable. On a loop-back (``review_verdicts`` present) the
    prompt instructs Claude to revise the prior plan against the feedback rather
    than start from scratch.

    ``context_provider`` is an optional WS5 injection seam. When set, it is
    called once and its result prepended to the prompt. Default None = identical
    behavior so existing callers are unaffected.
    """
    description = _task_description(state)
    qa = _format_qa_history(list(state.get("qa_history", [])))
    feedback = _format_review_feedback(list(state.get("review_verdicts", [])))
    prior_plan = state.get("plan")

    sections: list[str] = []
    # Optional memory/handbook context prepended when provider is injected (WS5).
    if context_provider is not None:
        try:
            ctx = context_provider()
        except Exception:  # noqa: BLE001
            ctx = ""
        if ctx:
            sections += [ctx, ""]

    sections += [
        "You are the PLANNER stage of an agentic SDLC pipeline. Produce a "
        "phased implementation plan for the task below. The clarifier has "
        "already reached confidence with the human, so do not ask questions — "
        "plan.",
        "",
        "## Task",
        description or "(no task description provided)",
    ]

    if qa:
        sections += ["", "## Clarified context (Q&A)", qa]

    if feedback:
        # Loop-back: the review stage sent the prior plan back for changes.
        sections += [
            "",
            "## Reviewer feedback on the previous plan (address every point)",
            feedback,
        ]
        if isinstance(prior_plan, dict) and prior_plan.get("phases"):
            sections += [
                "",
                "## Previous plan (revise; do not restart from scratch)",
                json.dumps(prior_plan, sort_keys=True, indent=2),
            ]

    sections += [
        "",
        "## Output format",
        "Return ONLY a JSON object with keys: "
        '"summary" (string), "phases" (a non-empty list of objects each with '
        '"name" and "steps", where "steps" is a non-empty list of strings). '
        "Do not include prose outside the JSON.",
    ]
    return "\n".join(sections)


def _strip_code_fence(text: str) -> str:
    """Strip a leading/trailing Markdown code fence if Claude wrapped the JSON."""
    fenced = re.match(
        r"^\s*```(?:json)?\s*\n(?P<body>.*?)\n?\s*```\s*$",
        text,
        flags=re.DOTALL | re.IGNORECASE,
    )
    if fenced:
        return fenced.group("body")
    return text


def parse_plan(text: str) -> dict[str, Any]:
    """Parse the model reply into a validated phased-plan dict.

    Raises :class:`PlannerError` if the reply is not a JSON object with a
    non-empty ``phases`` list of well-formed phases — a garbled plan must fail
    loudly so the coordinator does not advance an empty plan into review.
    """
    candidate = _strip_code_fence(text or "").strip()
    if not candidate:
        raise PlannerError("planner returned an empty response")
    try:
        data = json.loads(candidate)
    except json.JSONDecodeError as exc:
        raise PlannerError(f"planner reply was not valid JSON: {exc}") from exc

    if not isinstance(data, dict):
        raise PlannerError("planner reply JSON must be an object")

    phases = data.get("phases")
    if not isinstance(phases, list) or not phases:
        raise PlannerError("plan must contain a non-empty 'phases' list")

    normalized_phases: list[dict[str, Any]] = []
    for idx, phase in enumerate(phases, start=1):
        if not isinstance(phase, dict):
            raise PlannerError(f"phase {idx} must be an object")
        name = phase.get("name")
        steps = phase.get("steps")
        if not isinstance(name, str) or not name.strip():
            raise PlannerError(f"phase {idx} is missing a non-empty 'name'")
        if not isinstance(steps, list) or not steps:
            raise PlannerError(f"phase {idx} ('{name}') has no steps")
        normalized_steps = [str(step).strip() for step in steps if str(step).strip()]
        if not normalized_steps:
            raise PlannerError(f"phase {idx} ('{name}') has no non-empty steps")
        normalized_phases.append({"name": name.strip(), "steps": normalized_steps})

    summary = data.get("summary")
    return {
        "summary": str(summary).strip() if isinstance(summary, str) else "",
        "phases": normalized_phases,
    }


def _revision_count(state: PipelineState) -> int:
    """How many REQUEST-CHANGES loop-backs have happened so far (§3.3).

    Counts the request-changes verdicts already recorded in the state; the
    planner uses this to decide whether the next attempt is still within the
    convergence bound.
    """
    count = 0
    for verdict in state.get("review_verdicts", []):
        decision = (
            verdict.get("decision") if isinstance(verdict, dict) else str(verdict)
        )
        if isinstance(decision, str) and decision.strip().upper() == _REQUEST_CHANGES:
            count += 1
    return count


def plan_node(
    state: PipelineState,
    config: dict[str, Any] | None = None,
    *,
    context_provider: ContextProvider | None = None,
) -> PipelineState:
    """LangGraph node: draft/refine the phased plan, then advance to REVIEW.

    Returns a **partial** :class:`~agent_team.task_model.PipelineState` (the
    keys this node owns) — LangGraph merges it into the checkpointed state.

    Behaviour:

    * **Convergence bound (§3.3, §6.6).** If the review stage has already sent
      the plan back :data:`MAX_PLAN_REVISIONS` times, the planner does **not**
      burn more Claude budget: it parks the task (status ``PARKED``, phase
      ``PARKED``) so the coordinator ALARMs Adam. This is the "escalate to Adam
      if it cannot converge" path.
    * **Plan / re-plan.** Otherwise it builds the prompt (folding in any review
      feedback on a loop-back), calls :func:`claude_invoke`, parses the reply,
      and returns the new ``plan`` with the phase advanced to ``REVIEW``.

    ``config`` is forwarded to the billing seam so the caller can pin the
    billing mode (it is threaded through to :func:`claude_invoke` as ``config``).
    """
    revisions = _revision_count(state)
    if revisions >= MAX_PLAN_REVISIONS:
        # Escalation ladder (§5/§3.3): stop looping, hand to the human.
        return PipelineState(
            status=TaskStatus.PARKED.value,
            current_phase=Phase.PARKED.value,
        )

    prompt = build_plan_prompt(state, context_provider=context_provider)
    result: ClaudeResult = claude_invoke(prompt, config=config)
    plan = parse_plan(result.text)
    # Record how many times we have planned so review/observability can see it.
    plan["revision"] = revisions

    return PipelineState(
        plan=plan,
        current_phase=Phase.REVIEW.value,
        status=TaskStatus.ACTIVE.value,
    )