from datetime import datetime, timezone

from fastapi import APIRouter, Depends
from fastapi.responses import JSONResponse
from sqlalchemy import func, select, text
from sqlalchemy.ext.asyncio import AsyncSession

from api.database import get_session, engine
from api.models.decision import Decision, DecisionStatus, DecisionType
from api.models.progress_event import ProgressEvent
from api.models.task import Task, TaskStatus
from api.models.topic import Topic, TopicStatus
from api.models.workstream import Workstream, WorkstreamStatus
from api.schemas.decision import DecisionRead
from api.schemas.progress_event import ProgressEventRead
from api.schemas.state import (
    DecisionTotals,
    StateSummary,
    TaskTotals,
    Totals,
    TopicTotals,
    WorkstreamTotals,
)
from api.schemas.task import TaskRead
from api.schemas.topic import TopicWithWorkstreams
from api.schemas.workstream import WorkstreamRead

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


@router.get("/summary", response_model=StateSummary)
async def get_summary(session: AsyncSession = Depends(get_session)) -> StateSummary:
    # Run all queries sequentially on one session.
    # AsyncSession does not support concurrent operations (no gather on same session).

    topics_rows = await session.execute(
        select(Topic).where(Topic.status != TopicStatus.archived).order_by(Topic.created_at)
    )
    topics = list(topics_rows.scalars().all())

    blocking_rows = await session.execute(
        select(Decision)
        .where(Decision.decision_type == DecisionType.pending)
        .where(Decision.status.in_([DecisionStatus.open, DecisionStatus.escalated]))
        .order_by(Decision.deadline.asc().nullslast(), Decision.created_at)
    )
    blocking = list(blocking_rows.scalars().all())

    blocked_rows = await session.execute(
        select(Task).where(Task.status == TaskStatus.blocked).order_by(Task.created_at)
    )
    blocked = list(blocked_rows.scalars().all())

    recent_rows = await session.execute(
        select(ProgressEvent).order_by(ProgressEvent.created_at.desc()).limit(20)
    )
    recent = list(recent_rows.scalars().all())

    open_ws_rows = await session.execute(
        select(Workstream)
        .where(Workstream.status.in_([WorkstreamStatus.active, WorkstreamStatus.blocked]))
        .order_by(Workstream.due_date.asc().nullslast(), Workstream.created_at)
    )
    open_ws = list(open_ws_rows.scalars().all())

    # Totals — one GROUP BY per table
    topic_counts = {r[0]: r[1] for r in await session.execute(
        select(Topic.status, func.count()).group_by(Topic.status)
    )}
    ws_counts = {r[0]: r[1] for r in await session.execute(
        select(Workstream.status, func.count()).group_by(Workstream.status)
    )}
    task_counts = {r[0]: r[1] for r in await session.execute(
        select(Task.status, func.count()).group_by(Task.status)
    )}
    dec_counts = {r[0]: r[1] for r in await session.execute(
        select(Decision.status, func.count()).group_by(Decision.status)
    )}

    totals = Totals(
        topics=TopicTotals(
            active=topic_counts.get(TopicStatus.active, 0),
            paused=topic_counts.get(TopicStatus.paused, 0),
            archived=topic_counts.get(TopicStatus.archived, 0),
            total=sum(topic_counts.values()),
        ),
        workstreams=WorkstreamTotals(
            active=ws_counts.get(WorkstreamStatus.active, 0),
            blocked=ws_counts.get(WorkstreamStatus.blocked, 0),
            completed=ws_counts.get(WorkstreamStatus.completed, 0),
            archived=ws_counts.get(WorkstreamStatus.archived, 0),
            total=sum(ws_counts.values()),
        ),
        tasks=TaskTotals(
            todo=task_counts.get(TaskStatus.todo, 0),
            in_progress=task_counts.get(TaskStatus.in_progress, 0),
            blocked=task_counts.get(TaskStatus.blocked, 0),
            done=task_counts.get(TaskStatus.done, 0),
            cancelled=task_counts.get(TaskStatus.cancelled, 0),
            total=sum(task_counts.values()),
        ),
        decisions=DecisionTotals(
            open=dec_counts.get(DecisionStatus.open, 0),
            resolved=dec_counts.get(DecisionStatus.resolved, 0),
            escalated=dec_counts.get(DecisionStatus.escalated, 0),
            superseded=dec_counts.get(DecisionStatus.superseded, 0),
            total=sum(dec_counts.values()),
        ),
    )

    return StateSummary(
        generated_at=datetime.now(tz=timezone.utc),
        totals=totals,
        topics=[TopicWithWorkstreams.model_validate(t) for t in topics],
        blocking_decisions=[DecisionRead.model_validate(d) for d in blocking],
        blocked_tasks=[TaskRead.model_validate(t) for t in blocked],
        recent_progress=[ProgressEventRead.model_validate(e) for e in recent],
        open_workstreams=[WorkstreamRead.model_validate(w) for w in open_ws],
    )


@router.get("/health")
async def health_check() -> dict:
    try:
        async with engine.connect() as conn:
            await conn.execute(text("SELECT 1"))
        return {"status": "ok", "db": "connected"}
    except Exception as exc:
        return JSONResponse(
            status_code=503,
            content={"status": "error", "db": str(exc)},
        )