"""Registered project source metadata and refresh helpers."""

from __future__ import annotations

import json
from dataclasses import asdict, dataclass
from pathlib import Path

import atocore.config as _config
from atocore.ingestion.pipeline import ingest_folder


@dataclass(frozen=True)
class ProjectSourceRef:
    source: str
    subpath: str
    label: str = ""


@dataclass(frozen=True)
class RegisteredProject:
    project_id: str
    aliases: tuple[str, ...]
    description: str
    ingest_roots: tuple[ProjectSourceRef, ...]


def get_project_registry_template() -> dict:
    """Return a minimal template for registering a new project."""
    return {
        "projects": [
            {
                "id": "p07-example",
                "aliases": ["p07", "example-project"],
                "description": "Short description of the project and staged corpus.",
                "ingest_roots": [
                    {
                        "source": "vault",
                        "subpath": "incoming/projects/p07-example",
                        "label": "Primary staged project docs",
                    }
                ],
            }
        ]
    }


def build_project_registration_proposal(
    project_id: str,
    aliases: list[str] | tuple[str, ...] | None = None,
    description: str = "",
    ingest_roots: list[dict] | tuple[dict, ...] | None = None,
) -> dict:
    """Build a normalized project registration proposal without mutating state."""
    normalized_id = project_id.strip()
    if not normalized_id:
        raise ValueError("Project id must be non-empty")

    normalized_aliases = _normalize_aliases(aliases or [])
    normalized_roots = _normalize_ingest_roots(ingest_roots or [])
    if not normalized_roots:
        raise ValueError("At least one ingest root is required")

    collisions = _find_name_collisions(normalized_id, normalized_aliases)
    resolved_roots = []
    for root in normalized_roots:
        source_ref = ProjectSourceRef(
            source=root["source"],
            subpath=root["subpath"],
            label=root.get("label", ""),
        )
        resolved_path = _resolve_ingest_root(source_ref)
        resolved_roots.append(
            {
                **root,
                "path": str(resolved_path),
                "exists": resolved_path.exists(),
                "is_dir": resolved_path.is_dir(),
            }
        )

    return {
        "project": {
            "id": normalized_id,
            "aliases": normalized_aliases,
            "description": description.strip(),
            "ingest_roots": normalized_roots,
        },
        "resolved_ingest_roots": resolved_roots,
        "collisions": collisions,
        "registry_path": str(_config.settings.resolved_project_registry_path),
        "valid": not collisions,
    }


def register_project(
    project_id: str,
    aliases: list[str] | tuple[str, ...] | None = None,
    description: str = "",
    ingest_roots: list[dict] | tuple[dict, ...] | None = None,
) -> dict:
    """Persist a validated project registration to the registry file."""
    proposal = build_project_registration_proposal(
        project_id=project_id,
        aliases=aliases,
        description=description,
        ingest_roots=ingest_roots,
    )
    if not proposal["valid"]:
        collision_names = ", ".join(collision["name"] for collision in proposal["collisions"])
        raise ValueError(f"Project registration has collisions: {collision_names}")

    registry_path = _config.settings.resolved_project_registry_path
    payload = _load_registry_payload(registry_path)
    payload.setdefault("projects", []).append(proposal["project"])
    _write_registry_payload(registry_path, payload)

    return {
        **proposal,
        "status": "registered",
    }


def load_project_registry() -> list[RegisteredProject]:
    """Load project registry entries from JSON config."""
    registry_path = _config.settings.resolved_project_registry_path
    payload = _load_registry_payload(registry_path)
    entries = payload.get("projects", [])
    projects: list[RegisteredProject] = []

    for entry in entries:
        project_id = str(entry["id"]).strip()
        if not project_id:
            raise ValueError("Project registry entry is missing a non-empty id")
        aliases = tuple(
            alias.strip()
            for alias in entry.get("aliases", [])
            if isinstance(alias, str) and alias.strip()
        )
        description = str(entry.get("description", "")).strip()
        ingest_roots = tuple(
            ProjectSourceRef(
                source=str(root["source"]).strip(),
                subpath=str(root["subpath"]).strip(),
                label=str(root.get("label", "")).strip(),
            )
            for root in entry.get("ingest_roots", [])
            if str(root.get("source", "")).strip()
            and str(root.get("subpath", "")).strip()
        )
        if not ingest_roots:
            raise ValueError(f"Project registry entry '{project_id}' has no ingest_roots")
        projects.append(
            RegisteredProject(
                project_id=project_id,
                aliases=aliases,
                description=description,
                ingest_roots=ingest_roots,
            )
        )

    _validate_unique_project_names(projects)
    return projects


def list_registered_projects() -> list[dict]:
    """Return registry entries with resolved source readiness."""
    return [_project_to_dict(project) for project in load_project_registry()]


def get_registered_project(project_name: str) -> RegisteredProject | None:
    """Resolve a registry entry by id or alias."""
    needle = project_name.strip().lower()
    if not needle:
        return None

    for project in load_project_registry():
        candidates = {project.project_id.lower(), *(alias.lower() for alias in project.aliases)}
        if needle in candidates:
            return project
    return None


def refresh_registered_project(project_name: str, purge_deleted: bool = False) -> dict:
    """Ingest all configured source roots for a registered project."""
    project = get_registered_project(project_name)
    if project is None:
        raise ValueError(f"Unknown project: {project_name}")

    roots = []
    for source_ref in project.ingest_roots:
        resolved = _resolve_ingest_root(source_ref)
        root_result = {
            "source": source_ref.source,
            "subpath": source_ref.subpath,
            "label": source_ref.label,
            "path": str(resolved),
        }
        if not resolved.exists():
            roots.append({**root_result, "status": "missing"})
            continue
        if not resolved.is_dir():
            roots.append({**root_result, "status": "not_directory"})
            continue

        roots.append(
            {
                **root_result,
                "status": "ingested",
                "results": ingest_folder(resolved, purge_deleted=purge_deleted),
            }
        )

    return {
        "project": project.project_id,
        "aliases": list(project.aliases),
        "description": project.description,
        "purge_deleted": purge_deleted,
        "roots": roots,
    }


def _normalize_aliases(aliases: list[str] | tuple[str, ...]) -> list[str]:
    deduped: list[str] = []
    seen: set[str] = set()
    for alias in aliases:
        candidate = alias.strip()
        if not candidate:
            continue
        key = candidate.lower()
        if key in seen:
            continue
        seen.add(key)
        deduped.append(candidate)
    return deduped


def _normalize_ingest_roots(ingest_roots: list[dict] | tuple[dict, ...]) -> list[dict]:
    normalized: list[dict] = []
    for root in ingest_roots:
        source = str(root.get("source", "")).strip()
        subpath = str(root.get("subpath", "")).strip()
        label = str(root.get("label", "")).strip()
        if not source or not subpath:
            continue
        if source not in {"vault", "drive"}:
            raise ValueError(f"Unsupported source root: {source}")
        normalized.append({"source": source, "subpath": subpath, "label": label})
    return normalized


def _project_to_dict(project: RegisteredProject) -> dict:
    return {
        "id": project.project_id,
        "aliases": list(project.aliases),
        "description": project.description,
        "ingest_roots": [
            {
                **asdict(source_ref),
                "path": str(_resolve_ingest_root(source_ref)),
                "exists": _resolve_ingest_root(source_ref).exists(),
                "is_dir": _resolve_ingest_root(source_ref).is_dir(),
            }
            for source_ref in project.ingest_roots
        ],
    }


def _resolve_ingest_root(source_ref: ProjectSourceRef) -> Path:
    base_map = {
        "vault": _config.settings.resolved_vault_source_dir,
        "drive": _config.settings.resolved_drive_source_dir,
    }
    try:
        base_dir = base_map[source_ref.source]
    except KeyError as exc:
        raise ValueError(f"Unsupported source root: {source_ref.source}") from exc

    return (base_dir / source_ref.subpath).resolve(strict=False)


def _validate_unique_project_names(projects: list[RegisteredProject]) -> None:
    seen: dict[str, str] = {}
    for project in projects:
        names = [project.project_id, *project.aliases]
        for name in names:
            key = name.lower()
            if key in seen and seen[key] != project.project_id:
                raise ValueError(
                    f"Project registry name collision: '{name}' is used by both "
                    f"'{seen[key]}' and '{project.project_id}'"
                )
            seen[key] = project.project_id


def _find_name_collisions(project_id: str, aliases: list[str]) -> list[dict]:
    collisions: list[dict] = []
    existing = load_project_registry()
    requested_names = [project_id, *aliases]
    for requested in requested_names:
        requested_key = requested.lower()
        for project in existing:
            project_names = [project.project_id, *project.aliases]
            if requested_key in {name.lower() for name in project_names}:
                collisions.append(
                    {
                        "name": requested,
                        "existing_project": project.project_id,
                    }
                )
                break
    return collisions


def _load_registry_payload(registry_path: Path) -> dict:
    if not registry_path.exists():
        return {"projects": []}
    return json.loads(registry_path.read_text(encoding="utf-8"))


def _write_registry_payload(registry_path: Path, payload: dict) -> None:
    registry_path.parent.mkdir(parents=True, exist_ok=True)
    registry_path.write_text(
        json.dumps(payload, indent=2, ensure_ascii=True) + "\n",
        encoding="utf-8",
    )