import uuid
import socket
from pathlib import Path
from typing import Any

from fastapi import APIRouter, Depends, HTTPException, status
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from api.database import get_session
from api.models.managed_repo import ManagedRepo
from api.models.workstream import Workstream
from api.schemas.workstream import (
    WorkstreamCreate,
    WorkstreamRead,
    WorkstreamStatus,
    WorkstreamUpdate,
)

router = APIRouter(prefix="/workstreams", tags=["workstreams"])


def _repo_path(repo: ManagedRepo) -> Path | None:
    hostname = socket.gethostname()
    candidates = []
    host_paths = repo.host_paths or {}
    if host_paths.get(hostname):
        candidates.append(host_paths[hostname])
    if repo.local_path:
        candidates.append(repo.local_path)
    for raw in candidates:
        path = Path(raw).expanduser()
        if path.is_dir():
            return path
    return None


def _frontmatter(path: Path) -> dict[str, Any]:
    try:
        text = path.read_text(encoding="utf-8")
    except OSError:
        return {}
    if not text.startswith("---\n"):
        return {}
    end = text.find("\n---", 4)
    if end == -1:
        return {}

    data: dict[str, Any] = {}
    for raw_line in text[4:end].splitlines():
        line = raw_line.strip()
        if not line or line.startswith("#") or ":" not in line:
            continue
        key, value = line.split(":", 1)
        value = value.strip()
        if len(value) >= 2 and value[0] == value[-1] and value[0] in {"'", '"'}:
            value = value[1:-1]
        data[key.strip()] = value
    return data


@router.get("/", response_model=list[WorkstreamRead])
async def list_workstreams(
    topic_id: uuid.UUID | None = None,
    repo_id: uuid.UUID | None = None,
    repo_goal_id: uuid.UUID | None = None,
    status: WorkstreamStatus | None = None,
    owner: str | None = None,
    slug: str | None = None,
    session: AsyncSession = Depends(get_session),
) -> list[Workstream]:
    q = select(Workstream)
    if topic_id:
        q = q.where(Workstream.topic_id == topic_id)
    if repo_id:
        q = q.where(Workstream.repo_id == repo_id)
    if repo_goal_id:
        q = q.where(Workstream.repo_goal_id == repo_goal_id)
    if status:
        q = q.where(Workstream.status == status)
    if owner:
        q = q.where(Workstream.owner == owner)
    if slug:
        q = q.where(Workstream.slug == slug)
    q = q.order_by(
        Workstream.planning_priority.asc().nullslast(),
        Workstream.planning_order.asc().nullslast(),
        Workstream.updated_at.desc(),
    )
    result = await session.execute(q)
    return list(result.scalars().all())


@router.get("/workplan-index")
async def workplan_index(session: AsyncSession = Depends(get_session)) -> dict[str, Any]:
    """Map file-backed workstream ids to their local workplan filenames."""
    result = await session.execute(
        select(ManagedRepo).where(ManagedRepo.status == "active").order_by(ManagedRepo.slug)
    )
    index: dict[str, Any] = {}
    for repo in result.scalars().all():
        root = _repo_path(repo)
        if root is None:
            continue
        for directory, archived in (
            (root / "workplans", False),
            (root / "workplans" / "archived", True),
        ):
            if not directory.is_dir():
                continue
            for path in sorted(directory.glob("*.md")):
                data = _frontmatter(path)
                workstream_id = data.get("state_hub_workstream_id")
                if not workstream_id:
                    continue
                index[str(workstream_id)] = {
                    "filename": path.name,
                    "relative_path": str(path.relative_to(root)),
                    "repo_slug": repo.slug,
                    "archived": archived,
                }
    return {"workstreams": index}


@router.post("/", response_model=WorkstreamRead, status_code=status.HTTP_201_CREATED)
async def create_workstream(
    body: WorkstreamCreate,
    session: AsyncSession = Depends(get_session),
) -> Workstream:
    ws = Workstream(**body.model_dump())
    session.add(ws)
    await session.commit()
    await session.refresh(ws)
    return ws


@router.get("/{workstream_id}", response_model=WorkstreamRead)
async def get_workstream(
    workstream_id: uuid.UUID,
    session: AsyncSession = Depends(get_session),
) -> Workstream:
    ws = await session.get(Workstream, workstream_id)
    if ws is None:
        raise HTTPException(status_code=404, detail="Workstream not found")
    return ws


@router.patch("/{workstream_id}", response_model=WorkstreamRead)
async def update_workstream(
    workstream_id: uuid.UUID,
    body: WorkstreamUpdate,
    session: AsyncSession = Depends(get_session),
) -> Workstream:
    ws = await session.get(Workstream, workstream_id)
    if ws is None:
        raise HTTPException(status_code=404, detail="Workstream not found")
    for field, value in body.model_dump(exclude_unset=True).items():
        setattr(ws, field, value)
    await session.commit()
    await session.refresh(ws)
    return ws


@router.delete("/{workstream_id}", response_model=WorkstreamRead)
async def archive_workstream(
    workstream_id: uuid.UUID,
    session: AsyncSession = Depends(get_session),
) -> Workstream:
    ws = await session.get(Workstream, workstream_id)
    if ws is None:
        raise HTTPException(status_code=404, detail="Workstream not found")
    ws.status = "archived"
    await session.commit()
    await session.refresh(ws)
    return ws