"""Attribution module — shared between post_extract.py and merge.py.

Owns: parsing attribution from YAML frontmatter, validating role entries,
computing role counts for contributor upserts, building attribution blocks.

Avoids circular dependency between post_extract.py (validates attribution at
extraction time) and merge.py (records attribution at merge time). Both
import from this shared module.

Schema reference: schemas/attribution.md
Weights reference: schemas/contribution-weights.yaml

Epimetheus owns this module. Leo reviews changes.
"""

import logging
import re
from pathlib import Path

logger = logging.getLogger("pipeline.attribution")

VALID_ROLES = frozenset({"sourcer", "extractor", "challenger", "synthesizer", "reviewer"})

# Agent-owned branch prefixes — PRs from these branches get Pentagon-Agent trailer
# credit for challenger/synthesizer roles. Pipeline-infra branches (extract/ reweave/
# fix/ ingestion/) are deliberately excluded: they're automation, not contribution.
# Single source of truth; imported by contributor.py and backfill-events.py.
AGENT_BRANCH_PREFIXES = (
    "rio/", "theseus/", "leo/", "vida/", "astra/", "clay/", "oberon/",
)

# Handle sanity: lowercase alphanumerics, hyphens, underscores. 1-39 chars (matches
# GitHub's handle rules). Rejects garbage like "governance---meritocratic-voting-+-futarchy"
# or "sec-interpretive-release-s7-2026-09-(march-17" that upstream frontmatter hygiene
# bugs produce. Apply at parse time so bad handles never reach the contributors table.
_HANDLE_RE = re.compile(r"^[a-z0-9][a-z0-9_-]{0,38}$")


def _valid_handle(handle: str) -> bool:
    """Return True if handle matches the handle format (alphanum + _-, ≤39 chars)."""
    if not handle or not isinstance(handle, str):
        return False
    h = handle.strip().lower().lstrip("@")
    if h.endswith("-") or h.endswith("_"):
        return False
    return bool(_HANDLE_RE.match(h))


def _filter_valid_handles(result: dict) -> dict:
    """Drop entries with invalid handles from a parsed attribution dict."""
    filtered: dict[str, list[dict]] = {role: [] for role in VALID_ROLES}
    for role, entries in result.items():
        for entry in entries:
            if _valid_handle(entry.get("handle", "")):
                filtered[role].append(entry)
    return filtered


# ─── Handle normalization + kind classification (schema v24) ──────────────

# Known Pentagon agents. Used to classify contributor kind='agent' so the
# leaderboard can filter them out of the default person view.
PENTAGON_AGENTS = frozenset({
    "rio", "leo", "theseus", "vida", "clay", "astra",
    "oberon", "argus", "rhea", "ganymede", "epimetheus", "hermes", "ship",
    "pipeline",  # pipeline-owned commits (extract/*, reweave/*, fix/*)
})


def normalize_handle(handle: str, conn=None) -> str:
    """Canonicalize a handle: lowercase, strip @, resolve alias if conn provided.

    Examples:
      '@thesensatore' → 'thesensatore'
      'Cameron' → 'cameron' → 'cameron-s1' (via alias if seeded)
      'CNBC' → 'cnbc'

    Always lowercases and strips @ prefix. Alias resolution requires a conn
    argument (not always available at parse time; merge-time writer passes it).
    """
    if not handle:
        return ""
    h = handle.strip().lower().lstrip("@")
    if conn is None:
        return h
    try:
        row = conn.execute(
            "SELECT canonical FROM contributor_aliases WHERE alias = ?", (h,),
        ).fetchone()
        if row:
            return row["canonical"] if isinstance(row, dict) or hasattr(row, "keys") else row[0]
    except Exception:
        # Alias table might not exist yet on pre-v24 DBs — degrade gracefully.
        logger.debug("normalize_handle: alias lookup failed for %r", h, exc_info=True)
    return h


def classify_kind(handle: str) -> str:
    """Return 'agent' for known Pentagon agents, 'person' otherwise.

    The 'org' kind (CNBC, SpaceNews, etc.) is assigned by operator review,
    not inferred here. Keeping heuristics narrow: we know our own agents;
    everything else defaults to person until explicitly classified.
    """
    h = handle.strip().lower().lstrip("@")
    if h in PENTAGON_AGENTS:
        return "agent"
    return "person"


# ─── Parse attribution from claim content ──────────────────────────────────


def parse_attribution(fm: dict) -> dict[str, list[dict]]:
    """Extract attribution block from claim frontmatter.

    Returns {role: [{"handle": str, "agent_id": str|None, "context": str|None}]}
    Handles both nested YAML format and flat field format.
    """
    result = {role: [] for role in VALID_ROLES}

    attribution = fm.get("attribution")
    if isinstance(attribution, dict):
        # Nested format (from schema spec)
        for role in VALID_ROLES:
            entries = attribution.get(role, [])
            if isinstance(entries, list):
                for entry in entries:
                    if isinstance(entry, dict) and "handle" in entry:
                        result[role].append({
                            "handle": entry["handle"].strip().lower().lstrip("@"),
                            "agent_id": entry.get("agent_id"),
                            "context": entry.get("context"),
                        })
                    elif isinstance(entry, str):
                        result[role].append({"handle": entry.strip().lower().lstrip("@"), "agent_id": None, "context": None})
            elif isinstance(entries, str):
                # Single entry as string
                result[role].append({"handle": entries.strip().lower().lstrip("@"), "agent_id": None, "context": None})
        # Fall through to the filter at the end (don't early-return). The nested
        # block path was skipping the handle sanity filter, letting garbage like
        # "senator-elissa-slotkin-/-the-hill" through when it was written into
        # frontmatter during the legacy-fallback era.
        return _filter_valid_handles(result)

    # Flat format fallback (attribution_sourcer, attribution_extractor, etc.)
    for role in VALID_ROLES:
        flat_val = fm.get(f"attribution_{role}")
        if flat_val:
            if isinstance(flat_val, str):
                result[role].append({"handle": flat_val.strip().lower().lstrip("@"), "agent_id": None, "context": None})
            elif isinstance(flat_val, list):
                for v in flat_val:
                    if isinstance(v, str):
                        result[role].append({"handle": v.strip().lower().lstrip("@"), "agent_id": None, "context": None})

    # Bare-key flat format: `sourcer: alexastrum`, `extractor: leo`, etc.
    # This is what extract.py writes (line 290: f'sourcer: "{sourcer}"') — the most
    # common format in practice (~42% of claim files). The Apr 24 incident traced
    # missing leaderboard entries to this format being silently dropped because the
    # parser only checked the `attribution_*` prefix.
    # Only fill if the role wasn't already populated by the prefixed form, to avoid
    # double-counting when both formats coexist on the same claim.
    for role in VALID_ROLES:
        if result[role]:
            continue
        bare_val = fm.get(role)
        if isinstance(bare_val, str) and bare_val.strip():
            result[role].append({"handle": bare_val.strip().lower().lstrip("@"), "agent_id": None, "context": None})
        elif isinstance(bare_val, list):
            for v in bare_val:
                if isinstance(v, str) and v.strip():
                    result[role].append({"handle": v.strip().lower().lstrip("@"), "agent_id": None, "context": None})
                elif isinstance(v, dict) and v.get("handle"):
                    result[role].append({
                        "handle": v["handle"].strip().lower().lstrip("@"),
                        "agent_id": v.get("agent_id"),
                        "context": v.get("context"),
                    })

    # Legacy `source` heuristic REMOVED (Ganymede review, Apr 24). It fabricated
    # handles from descriptive source strings — "governance---meritocratic-voting-+-
    # futarchy", "cameron-(contributor)", "sec-interpretive-release-s7-2026-09-
    # (march-17". Hit rate on real handles was near-zero, false-positive rate was
    # high. Claims without explicit attribution now return empty (better surface as
    # data hygiene than invent fake contributors).

    # Filter to valid handles only. Bad handles (garbage from upstream frontmatter
    # bugs) get dropped rather than written to the contributors table.
    return _filter_valid_handles(result)


def parse_attribution_from_file(filepath: str) -> dict[str, list[dict]]:
    """Read a claim file and extract attribution. Returns role→entries dict."""
    try:
        content = Path(filepath).read_text()
    except (FileNotFoundError, PermissionError):
        return {role: [] for role in VALID_ROLES}

    from .post_extract import parse_frontmatter
    fm, _ = parse_frontmatter(content)
    if fm is None:
        return {role: [] for role in VALID_ROLES}

    return parse_attribution(fm)


# ─── Validate attribution ──────────────────────────────────────────────────


def validate_attribution(fm: dict, agent: str | None = None) -> list[str]:
    """Validate attribution block in claim frontmatter.

    Returns list of issues. Block on missing extractor, warn on missing sourcer.
    (Leo: extractor is always known, sourcer is best-effort.)

    If agent is provided and extractor is missing, auto-fix by setting the
    agent as extractor (same pattern as created-date auto-fix).

    Only validates if an attribution block is explicitly present. Legacy claims
    without attribution blocks are not blocked — they'll get attribution when
    enriched. New claims from v2 extraction always have attribution.
    """
    issues = []

    # Only validate if attribution block exists (don't break legacy claims)
    has_attribution = (
        fm.get("attribution") is not None
        or any(fm.get(f"attribution_{role}") for role in VALID_ROLES)
    )
    if not has_attribution:
        return []  # No attribution block = legacy claim, not an error

    attribution = parse_attribution(fm)

    if not attribution["extractor"]:
        if agent:
            # Auto-fix: set the processing agent as extractor
            attr = fm.get("attribution")
            if isinstance(attr, dict):
                attr["extractor"] = [{"handle": agent}]
            else:
                fm["attribution"] = {"extractor": [{"handle": agent}]}
            issues.append("fixed_missing_extractor")
        else:
            issues.append("missing_attribution_extractor")

    return issues


# ─── Build attribution block ──────────────────────────────────────────────


def build_attribution_block(
    agent: str,
    agent_id: str | None = None,
    source_handle: str | None = None,
    source_context: str | None = None,
) -> dict:
    """Build an attribution dict for a newly extracted claim.

    Called by openrouter-extract-v2.py when reconstructing claim content.
    """
    attribution = {
        "extractor": [{"handle": agent}],
        "sourcer": [],
        "challenger": [],
        "synthesizer": [],
        "reviewer": [],
    }

    if agent_id:
        attribution["extractor"][0]["agent_id"] = agent_id

    if source_handle:
        entry = {"handle": source_handle.strip().lower().lstrip("@")}
        if source_context:
            entry["context"] = source_context
        attribution["sourcer"].append(entry)

    return attribution


# ─── Compute role counts for contributor upserts ──────────────────────────


def role_counts_from_attribution(attribution: dict[str, list[dict]]) -> dict[str, list[str]]:
    """Extract {role: [handle, ...]} for contributor table upserts.

    Returns a dict mapping each role to the list of contributor handles.
    Used by merge.py to credit contributors after merge.
    """
    counts: dict[str, list[str]] = {}
    for role in VALID_ROLES:
        handles = [entry["handle"] for entry in attribution.get(role, []) if entry.get("handle")]
        if handles:
            counts[role] = handles
    return counts