"""Task board router — Taskz CRUD over Redis."""

from __future__ import annotations

import json
import re
from datetime import datetime, timezone
from typing import Any, Dict, List, Optional

from fastapi import APIRouter, Depends, HTTPException
from pydantic import BaseModel

from app.redis_client import (
    get_redis,
    get_board,
    list_boards,
    save_board,
    save_task,
    BOARD_KEY_PREFIX,
    BOARD_INDEX_KEY,
)

router = APIRouter(prefix="/api/v1", tags=["tasks"])


def _now() -> str:
    return datetime.now(timezone.utc).isoformat()


def _slugify(text: str) -> str:
    return re.sub(r"[^a-z0-9]+", "-", text.lower()).strip("-")[:20]


def _make_board_code(project: str, title: str) -> str:
    proj = re.sub(r"[^a-z0-9]+", "", project.lower())[:12].upper()
    title_word = re.sub(r"[^a-z0-9]+", "", title.lower().split()[0])[:6].upper()
    return f"{proj}-{title_word}"


def _next_task_number(board: Dict[str, Any]) -> int:
    tasks = board.get("tasks", [])
    return max((t.get("number", 0) for t in tasks), default=0) + 1


# ── Schemas ───────────────────────────────────────────────────────────────────

class BoardCreate(BaseModel):
    project: str
    title: str
    description: str = ""
    tags: List[str] = []


class TaskCreate(BaseModel):
    title: str
    description: str = ""
    priority: str = "medium"
    tags: List[str] = []
    scope: Optional[str] = None


class TaskUpdate(BaseModel):
    status: Optional[str] = None
    title: Optional[str] = None
    description: Optional[str] = None
    findings: Optional[str] = None
    priority: Optional[str] = None
    tags: Optional[List[str]] = None


class BoardStatusUpdate(BaseModel):
    new_status: str = "completed"


# ── Endpoints ─────────────────────────────────────────────────────────────────

@router.get("/boards")
def api_list_boards(project: Optional[str] = None, status: Optional[str] = None):
    r = get_redis()
    boards = list_boards(r, project=project, status=status)
    summaries = []
    for b in boards:
        tasks = b.get("tasks", [])
        done = sum(1 for t in tasks if t["status"] == "done")
        summaries.append({
            "board_id": b["board_id"],
            "board_code": b.get("board_code", ""),
            "project": b["project"],
            "title": b["title"],
            "description": b.get("description", ""),
            "status": b.get("status", "active"),
            "tags": b.get("tags", []),
            "task_count": len(tasks),
            "done_count": done,
            "created_at": b.get("created_at", ""),
            "updated_at": b.get("updated_at", ""),
        })
    return {"boards": summaries, "total": len(summaries)}


@router.post("/boards", status_code=201)
def api_create_board(body: BoardCreate):
    r = get_redis()
    code = _make_board_code(body.project, body.title)
    board_id = f"{_slugify(body.project)}-{_slugify(body.title)}-{_now()[:10].replace('-', '')}"
    board = {
        "board_id": board_id,
        "board_code": code,
        "project": body.project,
        "title": body.title,
        "description": body.description,
        "status": "active",
        "tags": body.tags,
        "tasks": [],
        "created_at": _now(),
        "updated_at": _now(),
    }
    save_board(r, board)
    return {"board_id": board_id, "board_code": code}


@router.get("/boards/{board_id}")
def api_get_board(board_id: str):
    r = get_redis()
    board = get_board(r, board_id)
    if not board:
        raise HTTPException(status_code=404, detail="Board not found")
    return board


@router.patch("/boards/{board_id}/status")
def api_close_board(board_id: str, body: BoardStatusUpdate):
    r = get_redis()
    board = get_board(r, board_id)
    if not board:
        raise HTTPException(status_code=404, detail="Board not found")
    board["status"] = body.new_status
    board["updated_at"] = _now()
    save_board(r, board)
    return {"board_id": board_id, "status": body.new_status}


@router.post("/boards/{board_id}/tasks", status_code=201)
def api_add_task(board_id: str, body: TaskCreate):
    r = get_redis()
    board = get_board(r, board_id)
    if not board:
        raise HTTPException(status_code=404, detail="Board not found")
    code = board.get("board_code", board_id.upper()[:10])
    num = _next_task_number(board)
    task_id = f"{code}-{num:03d}"
    task: Dict[str, Any] = {
        "task_id": task_id,
        "board_id": board_id,
        "number": num,
        "title": body.title,
        "description": body.description,
        "priority": body.priority,
        "status": "pending",
        "tags": body.tags,
        "scope": body.scope,
        "findings": [],
        "created_at": _now(),
        "updated_at": _now(),
    }
    save_task(r, task)
    return {"task_id": task_id}


@router.patch("/tasks/{task_id}")
def api_update_task(task_id: str, body: TaskUpdate):
    r = get_redis()
    # find the task inside any board
    from app.redis_client import list_boards as _lb, TASK_KEY_PREFIX
    raw = r.get(f"{TASK_KEY_PREFIX}{task_id}")
    if not raw:
        # fallback: scan boards
        for board in _lb(r):
            task = next((t for t in board.get("tasks", []) if t["task_id"] == task_id), None)
            if task:
                raw = json.dumps(task)
                break
    if not raw:
        raise HTTPException(status_code=404, detail="Task not found")
    task = json.loads(raw)

    valid_statuses = {"pending", "in_progress", "done", "blocked", "wont_do"}
    valid_priorities = {"low", "medium", "high", "critical"}

    if body.status:
        if body.status not in valid_statuses:
            raise HTTPException(status_code=400, detail=f"Invalid status: {body.status}")
        task["status"] = body.status
        if body.status == "done":
            task["completed_at"] = _now()
    if body.title:
        task["title"] = body.title
    if body.description is not None:
        task["description"] = body.description
    if body.findings:
        findings = task.setdefault("findings", [])
        findings.append({"text": body.findings, "at": _now()})
    if body.priority:
        if body.priority not in valid_priorities:
            raise HTTPException(status_code=400, detail=f"Invalid priority: {body.priority}")
        task["priority"] = body.priority
    if body.tags is not None:
        task["tags"] = body.tags
    task["updated_at"] = _now()
    save_task(r, task)
    return {"task_id": task_id, "status": task["status"]}


@router.delete("/tasks/{task_id}")
def api_delete_task(task_id: str):
    r = get_redis()
    from app.redis_client import TASK_KEY_PREFIX
    raw = r.get(f"{TASK_KEY_PREFIX}{task_id}")
    if not raw:
        raise HTTPException(status_code=404, detail="Task not found")
    task = json.loads(raw)
    board = get_board(r, task["board_id"])
    if board:
        board["tasks"] = [t for t in board.get("tasks", []) if t["task_id"] != task_id]
        board["updated_at"] = _now()
        save_board(r, board)
    r.delete(f"{TASK_KEY_PREFIX}{task_id}")
    return {"deleted": task_id}