"""§22.2 project registry mirror — the config-side analogue of
cache.refresh_meta_repo.

A deployment declares its projects in a `projects.yaml` at the root of
REGISTRY_REPO. This module mirrors that file into the `projects` cache table
and the `deployment` singleton. Per §22.2, `projects` rows flow from the
registry only — never from user actions. The mirror runs on the registry-repo
webhook and on every reconciler sweep (Option A wiring, Task 5).
"""
from __future__ import annotations

import base64
import json
import logging
import re
from dataclasses import dataclass, field

import yaml

from . import db
from .config import Config
from .gitea import Gitea

log = logging.getLogger(__name__)

VALID_TYPES = {"document", "specification", "bdd"}
VALID_VISIBILITY = {"gated", "public", "unlisted"}
VALID_INITIAL_STATE = {"super-draft", "active"}
# §22.4b: per-type default landing state.
_TYPE_DEFAULT_INITIAL_STATE = {
    "document": "super-draft",
    "specification": "super-draft",
    "bdd": "active",
}
_SLUG_RE = re.compile(r"^[a-z0-9][a-z0-9-]*$")


class RegistryError(Exception):
    """A registry document that fails validation, or a missing registry file.

    Raised by parse_registry/refresh_registry. The caller decides severity:
    fatal at startup (no last-good to serve), tolerated on a running deployment
    (keep the last-good projects rows). See Task 5 wiring.
    """


@dataclass
class ProjectEntry:
    id: str
    name: str
    type: str
    content_repo: str
    visibility: str
    initial_state: str
    config: dict = field(default_factory=dict)  # theme, enabled_models


@dataclass
class RegistryDoc:
    deployment_name: str
    deployment_tagline: str
    projects: list[ProjectEntry]


def parse_registry(text: str) -> RegistryDoc:
    """Parse + validate projects.yaml. Pure (no I/O). Raises RegistryError."""
    raw = yaml.safe_load(text) or {}
    dep = raw.get("deployment") or {}
    projects_raw = raw.get("projects") or []
    if not isinstance(projects_raw, list) or not projects_raw:
        raise RegistryError("registry must declare at least one project")
    seen: set[str] = set()
    entries: list[ProjectEntry] = []
    for p in projects_raw:
        pid = str(p.get("id") or "").strip()
        if not _SLUG_RE.match(pid):
            raise RegistryError(f"project id {pid!r} is not a valid slug")
        if pid in seen:
            raise RegistryError(f"duplicate project id {pid!r}")
        seen.add(pid)
        name = str(p.get("name") or "").strip()
        if not name:
            raise RegistryError(f"project {pid!r} missing name")
        ptype = str(p.get("type") or "").strip()
        if ptype not in VALID_TYPES:
            raise RegistryError(f"project {pid!r} has invalid type {ptype!r}")
        content_repo = str(p.get("content_repo") or "").strip()
        if not content_repo:
            raise RegistryError(f"project {pid!r} missing content_repo")
        vis = str(p.get("visibility") or "gated").strip()
        if vis not in VALID_VISIBILITY:
            raise RegistryError(f"project {pid!r} has invalid visibility {vis!r}")
        initial_state = str(
            p.get("initial_state") or _TYPE_DEFAULT_INITIAL_STATE[ptype]
        ).strip()
        if initial_state not in VALID_INITIAL_STATE:
            raise RegistryError(
                f"project {pid!r} has invalid initial_state {initial_state!r}"
            )
        cfg: dict = {}
        if p.get("theme") is not None:
            cfg["theme"] = p["theme"]
        if p.get("enabled_models") is not None:
            cfg["enabled_models"] = [str(m) for m in p["enabled_models"]]
        entries.append(
            ProjectEntry(pid, name, ptype, content_repo, vis, initial_state, cfg)
        )
    return RegistryDoc(
        deployment_name=str(dep.get("name") or "").strip(),
        deployment_tagline=str(dep.get("tagline") or "").strip(),
        projects=entries,
    )


def apply_registry(doc: RegistryDoc, registry_sha: str) -> None:
    """Upsert the parsed registry into projects + deployment. Idempotent.

    §22.4a: `type` is immutable — a change against an existing row is rejected
    (skip + log), never applied. Projects absent from the registry are left in
    place (archival is out of scope for M3; they simply stop refreshing).
    """
    conn = db.conn()
    for e in doc.projects:
        existing = conn.execute(
            "SELECT type FROM projects WHERE id = ?", (e.id,)
        ).fetchone()
        if existing is not None and existing["type"] not in (None, "", e.type):
            log.error(
                "registry: refusing immutable type change on project %s (%s -> %s)",
                e.id, existing["type"], e.type,
            )
            continue
        conn.execute(
            """
            INSERT INTO projects
                (id, name, type, content_repo, visibility, initial_state,
                 config_json, registry_sha, updated_at)
            VALUES (?, ?, ?, ?, ?, ?, ?, ?, datetime('now'))
            ON CONFLICT(id) DO UPDATE SET
                name = excluded.name,
                type = excluded.type,
                content_repo = excluded.content_repo,
                visibility = excluded.visibility,
                initial_state = excluded.initial_state,
                config_json = excluded.config_json,
                registry_sha = excluded.registry_sha,
                updated_at = datetime('now')
            """,
            (
                e.id, e.name, e.type, e.content_repo, e.visibility,
                e.initial_state, json.dumps(e.config), registry_sha,
            ),
        )
    conn.execute(
        """
        UPDATE deployment
           SET name = ?, tagline = ?, registry_sha = ?, updated_at = datetime('now')
         WHERE id = 1
        """,
        (doc.deployment_name, doc.deployment_tagline, registry_sha),
    )


async def refresh_registry(config: Config, gitea: Gitea) -> None:
    """Mirror REGISTRY_REPO/projects.yaml into projects + deployment.

    Idempotent. Raises RegistryError on a missing/invalid file and GiteaError
    on transport failure; the caller chooses fatal-vs-tolerated.
    """
    item = await gitea.get_contents(
        config.gitea_org, config.registry_repo, "projects.yaml", ref="main"
    )
    if not item or item.get("type") != "file":
        raise RegistryError(
            f"{config.gitea_org}/{config.registry_repo}/projects.yaml not found"
        )
    text = base64.b64decode(item["content"]).decode("utf-8")
    sha = item.get("last_commit_sha") or item.get("sha") or ""
    doc = parse_registry(text)
    apply_registry(doc, sha)
    log.info("registry: mirrored %d project(s) at %s", len(doc.projects), sha)