"""Prompt-build / reply-parse split for the Confluence-writer node.

This module is the pure, model-output-facing half of the Confluence-writer
stage — the same ``build_*_prompt`` / ``parse_*_reply`` split
:mod:`agent_team.nodes.planner` (``build_plan_prompt`` / ``parse_plan``) and
:mod:`agent_team.nodes.clarifier_llm` (``ClaudeClarifier._build_prompt`` /
``_parse``) use, so the node body (:mod:`agent_team.nodes.confluence_writer`)
stays a thin LangGraph state-transition wrapper.

The Confluence-writer node drafts a **Confluence page update** as DATA (it never
writes to a repo, and it never posts to Confluence from the draft node — the
write is a later, dry-run-by-default node). Two source flows feed the draft:

* **Flow A** — a direct documentation ask: the draft is built from the task
  description alone (``state['task']``).
* **Flow B** — a post-build documentation update: the draft folds in the
  approved ``plan``, the ``candidate_diff``, and the repo name so the page
  reflects what the change actually did.

On a ``request_changes`` loop-back the prior gate's ``confluence_feedback`` is
folded into the prompt so the redraft answers the reviewer's notes (mirrors the
planner's ``_format_review_feedback`` loop-back).

The LLM binding is an INJECTED seam (``context_provider``), exactly like the
planner's, so the prompt assembly stays pure and unit-testable and no live model
is bound here.

Parsing is DEFENSIVE: the model output is UNTRUSTED. A garbled reply must not
silently produce an empty page write, so :func:`parse_confluence_reply` raises
:class:`ConfluenceDraftError` when it cannot recover a usable
``{title, body_storage}`` draft, and the node decides what to do with that.
"""

from __future__ import annotations

import json
import re
from collections.abc import Callable, Mapping, Sequence
from typing import Any

from agent_team.task_model import PipelineState

# Optional context-provider callable (mirrors planner.ContextProvider): () -> str.
# When injected, its result is prepended to the Confluence-writer prompt. Default
# None = unchanged behavior so existing callers are unaffected.
ContextProvider = Callable[[], str]

__all__ = [
    "ConfluenceDraftError",
    "build_confluence_prompt",
    "parse_confluence_reply",
]


class ConfluenceDraftError(Exception):
    """Raised when the model reply cannot be parsed into a usable draft.

    Distinct from a *gate rejection* (which loops back through the human gate):
    this signals the draft model output itself was empty/garbled, so the node
    can fail loudly rather than advance an empty page update toward a write.
    """


def _task_description(state: PipelineState) -> str:
    """Pull the task description out of the graph state (mirrors planner.py)."""
    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 _repo_name(state: PipelineState) -> str:
    """Pull the repo name out of the graph state (Flow B), defensively.

    Looked for under a top-level ``repo`` key and, failing that, inside the plan
    dict — the same conventional places the clarifier reads ``repo`` from. An
    absent repo yields an empty string so the prompt section is simply omitted.
    """
    repo = state.get("repo")  # type: ignore[call-overload]
    if isinstance(repo, str) and repo.strip():
        return repo.strip()
    plan = state.get("plan") or {}
    if isinstance(plan, dict):
        repo = plan.get("repo")
        if isinstance(repo, str) and repo.strip():
            return repo.strip()
    return ""


def _candidate_diff(state: PipelineState) -> str:
    """Pull the candidate diff (Flow B) out of the graph state, defensively."""
    diff = state.get("candidate_diff")
    if isinstance(diff, str) and diff.strip():
        return diff.strip()
    return ""


def _format_plan(plan: Any) -> str:
    """Render the approved plan into prompt text (Flow B)."""
    if not isinstance(plan, Mapping):
        return ""
    try:
        return json.dumps(dict(plan), sort_keys=True, indent=2)
    except (TypeError, ValueError):
        return repr(plan)


def _truncate(text: str, limit: int) -> str:
    """Truncate ``text`` to ``limit`` chars with a marker (keep prompts bounded).

    A candidate diff can be large; the draft only needs enough of it to describe
    the change, so we cap it rather than blow the context budget.
    """
    if len(text) <= limit:
        return text
    return text[:limit] + f"\n... [truncated {len(text) - limit} chars]"


def build_confluence_prompt(
    state: PipelineState,
    *,
    context_provider: ContextProvider | None = None,
) -> str:
    """Build the Claude prompt that drafts a Confluence page update.

    Pure string assembly over the graph state — no I/O — so the prompt shape is
    directly unit-testable (mirrors :func:`planner.build_plan_prompt`).

    Source selection:

    * **Flow A** (no plan/diff) — the draft is built from ``state['task']``.
    * **Flow B** (plan and/or candidate diff present) — the draft folds in the
      approved plan, the candidate diff, and the repo name.

    On a ``request_changes`` loop-back the prior ``confluence_feedback`` is
    folded in so the redraft addresses every note (mirrors the planner's
    review-feedback loop-back). ``context_provider`` is the optional injection
    seam: when set it is called once and its result prepended (and a raising
    provider degrades to an empty prefix, never a crash).
    """
    description = _task_description(state)
    repo = _repo_name(state)
    diff = _candidate_diff(state)
    plan = state.get("plan")
    plan_text = _format_plan(plan)
    feedback = state.get("confluence_feedback")
    flow_b = bool(plan_text or diff)

    sections: list[str] = []

    if context_provider is not None:
        try:
            ctx = context_provider()
        except Exception:  # noqa: BLE001 - a context provider must never crash the draft
            ctx = ""
        if ctx:
            sections += [ctx, ""]

    sections += [
        "You are the CONFLUENCE-WRITER stage of an agentic SDLC pipeline. "
        "Inspect the repository (read-only) and draft a Confluence page update "
        "that documents this work. Emit the draft as DATA only — do NOT edit, "
        "create, or write any files, and do NOT post to Confluence; a later "
        "human-gated node performs the actual write.",
        "",
        "## Task",
        description or "(no task description provided)",
    ]

    if repo:
        sections += ["", "## Repository", repo]

    if flow_b:
        if plan_text:
            sections += ["", "## Approved plan (what was decided)", plan_text]
        if diff:
            sections += [
                "",
                "## Candidate diff (what the change actually did)",
                _truncate(diff, 8000),
            ]
        sections += [
            "",
            "## Documentation intent",
            "Update the Confluence page so it reflects the architecture AFTER "
            "this change: new/removed/modified resources, data flow, and "
            "configuration. If the page carries an architecture diagram macro, "
            "describe the mermaid edits needed rather than rewriting unrelated "
            "content.",
        ]
    else:
        sections += [
            "",
            "## Documentation intent",
            "Draft the Confluence page update this documentation task asks for.",
        ]

    if isinstance(feedback, str) and feedback.strip():
        sections += [
            "",
            "## Reviewer feedback on the previous draft (address every point)",
            feedback.strip(),
        ]

    sections += [
        "",
        "## Output format",
        "Return ONLY a JSON object with keys: "
        '"title" (string, the page title), '
        '"body_storage" (string, the page body in Confluence STORAGE format / '
        "XHTML), "
        '"page_id" (optional string, the id of an existing page to update; omit '
        "or null to create), and "
        '"mermaid_edits" (optional list of objects each with "macro_id" or '
        '"anchor" and a "mermaid" string, for architecture-diagram macro '
        "updates). Do not include prose outside the JSON. Do NOT use any "
        "write/edit tools.",
    ]
    return "\n".join(sections)


# A fenced ```...``` block, if the model wrapped its JSON in Markdown.
_FENCE_RE = re.compile(
    r"```(?:json)?\s*\n?(?P<body>.*?)\n?\s*```",
    flags=re.DOTALL | re.IGNORECASE,
)


def _strip_code_fence(text: str) -> str:
    """Strip a leading/trailing Markdown code fence if present (mirrors planner)."""
    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 _first_brace_span(text: str) -> str | None:
    """Return the first balanced ``{...}`` span in ``text`` (string-aware)."""
    start = text.find("{")
    if start == -1:
        return None
    depth = 0
    in_string = False
    escaped = False
    for idx in range(start, len(text)):
        ch = text[idx]
        if in_string:
            if escaped:
                escaped = False
            elif ch == "\\":
                escaped = True
            elif ch == '"':
                in_string = False
            continue
        if ch == '"':
            in_string = True
        elif ch == "{":
            depth += 1
        elif ch == "}":
            depth -= 1
            if depth == 0:
                return text[start : idx + 1]
    return None


def _extract_json_object(text: str) -> dict[str, Any] | None:
    """Extract a JSON object from UNTRUSTED model output, or ``None``.

    Tolerates the common deviations from "JSON only" (leading apology, trailing
    prose, ```json fences) by trying, in order: the whole string, the fenced
    block body, then the first balanced ``{...}`` span. Returns ``None`` (never
    raises) when nothing parses to a JSON object.
    """
    if not isinstance(text, str) or not text.strip():
        return None
    candidates: list[str] = [_strip_code_fence(text).strip(), text.strip()]
    fence = _FENCE_RE.search(text)
    if fence:
        candidates.append(fence.group("body").strip())
    span = _first_brace_span(text)
    if span is not None:
        candidates.append(span)
    for candidate in candidates:
        if not candidate:
            continue
        try:
            parsed = json.loads(candidate)
        except (json.JSONDecodeError, ValueError):
            continue
        if isinstance(parsed, dict):
            return parsed
    return None


def _coerce_mermaid_edits(value: Any) -> list[dict[str, Any]]:
    """Coerce the optional ``mermaid_edits`` into a clean list of edit dicts.

    Each kept entry must carry a non-empty ``mermaid`` string; an anchor is kept
    when present (either ``macro_id`` or ``anchor``). Anything malformed is
    dropped so a garbled edit can never silently corrupt a macro update.
    """
    if not isinstance(value, Sequence) or isinstance(value, (str, bytes)):
        return []
    edits: list[dict[str, Any]] = []
    for item in value:
        if not isinstance(item, Mapping):
            continue
        mermaid = item.get("mermaid")
        if not isinstance(mermaid, str) or not mermaid.strip():
            continue
        edit: dict[str, Any] = {"mermaid": mermaid.strip()}
        macro_id = item.get("macro_id")
        anchor = item.get("anchor")
        if isinstance(macro_id, str) and macro_id.strip():
            edit["macro_id"] = macro_id.strip()
        if isinstance(anchor, str) and anchor.strip():
            edit["anchor"] = anchor.strip()
        edits.append(edit)
    return edits


def parse_confluence_reply(text: str) -> dict[str, Any]:
    """Parse the model reply into a validated ``confluence_draft`` dict.

    Returns ``{title, body_storage, page_id?, mermaid_edits?}``:

    * ``title`` — non-empty page title (required);
    * ``body_storage`` — the Confluence storage-format body (required);
    * ``page_id`` — included only when the model named an existing page;
    * ``mermaid_edits`` — included only when at least one well-formed edit was
      supplied.

    Raises :class:`ConfluenceDraftError` when the reply is empty, not a JSON
    object, or missing a usable ``title`` / ``body_storage`` — a garbled draft
    must fail loudly so the node never advances an empty page write.
    """
    data = _extract_json_object(text or "")
    if data is None:
        raise ConfluenceDraftError(
            "confluence draft reply was empty or not a JSON object"
        )

    title = data.get("title")
    if not isinstance(title, str) or not title.strip():
        raise ConfluenceDraftError("confluence draft is missing a non-empty 'title'")

    body = data.get("body_storage")
    if not isinstance(body, str) or not body.strip():
        raise ConfluenceDraftError(
            "confluence draft is missing a non-empty 'body_storage'"
        )

    draft: dict[str, Any] = {
        "title": title.strip(),
        "body_storage": body,
    }

    page_id = data.get("page_id")
    if isinstance(page_id, (str, int)) and str(page_id).strip():
        page_id_str = str(page_id).strip()
        # Confluence content ids are numeric. Reject anything else: a non-numeric
        # value (e.g. "123?expand=foo" or "123/child/456") would, if interpolated
        # into the REST path, rewrite the authenticated request — a request-path
        # injection carrying the service-account credential.
        if not re.fullmatch(r"[0-9]+", page_id_str):
            raise ConfluenceDraftError(
                "confluence draft 'page_id' must be numeric (a Confluence content id)"
            )
        draft["page_id"] = page_id_str

    mermaid_edits = _coerce_mermaid_edits(data.get("mermaid_edits"))
    if mermaid_edits:
        draft["mermaid_edits"] = mermaid_edits

    return draft