import os
from datetime import datetime, timezone
from typing import Any, Dict, Optional, Tuple

from flask import Flask, jsonify, request
try:
    from flask_cors import CORS
except Exception:  # pragma: no cover
    CORS = None  # type: ignore

from db import Database


def _get_env(name: str, default: Optional[str] = None) -> str:
    value = os.environ.get(name)
    return value if value is not None else (default if default is not None else "")


def _normalize_iso8601(timestamp_str: str) -> str:
    if not isinstance(timestamp_str, str) or not timestamp_str:
        return datetime.now(timezone.utc).isoformat()
    ts = timestamp_str.strip()
    if ts.endswith("Z"):
        ts = ts[:-1] + "+00:00"
    try:
        parsed = datetime.fromisoformat(ts)
        if parsed.tzinfo is None:
            parsed = parsed.replace(tzinfo=timezone.utc)
        return parsed.astimezone(timezone.utc).isoformat()
    except Exception:
        return datetime.now(timezone.utc).isoformat()


def _validate_reading_payload(payload: Dict[str, Any], partial: bool = False) -> Tuple[Optional[Dict[str, Any]], Optional[str]]:
    allowed_keys = {"device_id", "timestamp", "pressure", "voltage"}
    if not isinstance(payload, dict):
        return None, "Invalid JSON body"

    for key in payload.keys():
        if key not in allowed_keys:
            return None, f"Unexpected field: {key}"

    if not partial:
        missing = [k for k in ["device_id", "pressure", "voltage"] if k not in payload]
        if missing:
            return None, f"Missing required fields: {', '.join(missing)}"

    result: Dict[str, Any] = {}

    if "device_id" in payload:
        if not isinstance(payload["device_id"], str) or not payload["device_id"].strip():
            return None, "device_id must be a non-empty string"
        result["device_id"] = payload["device_id"].strip()

    if "timestamp" in payload:
        result["timestamp"] = _normalize_iso8601(str(payload["timestamp"]))
    elif not partial:
        result["timestamp"] = datetime.now(timezone.utc).isoformat()

    if "pressure" in payload:
        try:
            result["pressure"] = float(payload["pressure"])
        except Exception:
            return None, "pressure must be a number"

    if "voltage" in payload:
        try:
            result["voltage"] = float(payload["voltage"])
        except Exception:
            return None, "voltage must be a number"

    return result, None


app = Flask(__name__)
if CORS is not None:
    CORS(app, resources={r"/*": {"origins": "*"}}, supports_credentials=False)

DB_PATH = _get_env("DB_PATH", os.path.join(os.path.dirname(__file__), "readings.db"))
database = Database(DB_PATH)
database.init_db()


@app.get("/health")
def health() -> Any:
    return jsonify({"ok": True})


@app.post("/data")
def ingest_from_device() -> Any:
    payload = request.get_json(silent=True) or {}
    data, error = _validate_reading_payload(payload, partial=False)
    if error:
        return jsonify({"ok": False, "error": error}), 400
    new_id = database.insert_reading(data)
    return jsonify({"ok": True, "id": new_id}), 201


@app.get("/api/readings")
def list_readings() -> Any:
    device_id = request.args.get("device_id")
    start = request.args.get("start")
    end = request.args.get("end")
    sort = (request.args.get("sort") or "desc").lower()
    sort = "asc" if sort == "asc" else "desc"

    try:
        page = int(request.args.get("page", 1))
        page_size = int(request.args.get("page_size", 50))
    except Exception:
        return jsonify({"ok": False, "error": "page and page_size must be integers"}), 400

    page = max(1, page)
    page_size = min(max(1, page_size), 500)

    filters: Dict[str, Any] = {}
    if device_id:
        filters["device_id"] = device_id
    if start:
        filters["start"] = _normalize_iso8601(start)
    if end:
        filters["end"] = _normalize_iso8601(end)
    # 可选压力范围过滤，用于图表或报警检索
    min_p = request.args.get("min_pressure")
    max_p = request.args.get("max_pressure")
    if min_p is not None:
        try:
            filters["min_pressure"] = float(min_p)
        except Exception:
            return jsonify({"ok": False, "error": "min_pressure must be a number"}), 400
    if max_p is not None:
        try:
            filters["max_pressure"] = float(max_p)
        except Exception:
            return jsonify({"ok": False, "error": "max_pressure must be a number"}), 400

    total = database.count_readings(filters)
    items = database.list_readings(filters, sort=sort, limit=page_size, offset=(page - 1) * page_size)

    return jsonify({
        "ok": True,
        "total": total,
        "page": page,
        "page_size": page_size,
        "items": items,
    })


@app.get("/api/readings/latest")
def latest_reading() -> Any:
    device_id = request.args.get("device_id")
    row = database.get_latest_reading(device_id)
    if not row:
        return jsonify({"ok": False, "error": "Not found"}), 404
    return jsonify({"ok": True, "item": row})


@app.get("/api/alarms")
def list_alarms() -> Any:
    device_id = request.args.get("device_id")
    start = request.args.get("start")
    end = request.args.get("end")
    min_p = request.args.get("min_pressure")
    max_p = request.args.get("max_pressure")

    if min_p is None and max_p is None:
        return jsonify({"ok": False, "error": "min_pressure or max_pressure is required"}), 400

    try:
        page = int(request.args.get("page", 1))
        page_size = int(request.args.get("page_size", 50))
    except Exception:
        return jsonify({"ok": False, "error": "page and page_size must be integers"}), 400

    page = max(1, page)
    page_size = min(max(1, page_size), 500)

    filters: Dict[str, Any] = {}
    if device_id:
        filters["device_id"] = device_id
    if start:
        filters["start"] = _normalize_iso8601(start)
    if end:
        filters["end"] = _normalize_iso8601(end)
    if min_p is not None:
        try:
            filters["min_pressure"] = float(min_p)
        except Exception:
            return jsonify({"ok": False, "error": "min_pressure must be a number"}), 400
    if max_p is not None:
        try:
            filters["max_pressure"] = float(max_p)
        except Exception:
            return jsonify({"ok": False, "error": "max_pressure must be a number"}), 400

    total = database.count_readings(filters)
    items = database.list_readings(filters, sort="desc", limit=page_size, offset=(page - 1) * page_size)

    return jsonify({
        "ok": True,
        "total": total,
        "page": page,
        "page_size": page_size,
        "items": items,
    })


@app.get("/api/readings/<int:reading_id>")
def get_reading(reading_id: int) -> Any:
    row = database.get_reading(reading_id)
    if not row:
        return jsonify({"ok": False, "error": "Not found"}), 404
    return jsonify({"ok": True, "item": row})


@app.post("/api/readings")
def create_reading() -> Any:
    payload = request.get_json(silent=True) or {}
    data, error = _validate_reading_payload(payload, partial=False)
    if error:
        return jsonify({"ok": False, "error": error}), 400
    new_id = database.insert_reading(data)
    return jsonify({"ok": True, "id": new_id}), 201


@app.put("/api/readings/<int:reading_id>")
def update_reading(reading_id: int) -> Any:
    payload = request.get_json(silent=True) or {}
    data, error = _validate_reading_payload(payload, partial=True)
    if error:
        return jsonify({"ok": False, "error": error}), 400
    if not data:
        return jsonify({"ok": False, "error": "Empty body"}), 400
    updated = database.update_reading(reading_id, data)
    if not updated:
        return jsonify({"ok": False, "error": "Not found"}), 404
    return jsonify({"ok": True})


@app.delete("/api/readings/<int:reading_id>")
def delete_reading(reading_id: int) -> Any:
    deleted = database.delete_reading(reading_id)
    if not deleted:
        return jsonify({"ok": False, "error": "Not found"}), 404
    return jsonify({"ok": True})


if __name__ == "__main__":
    host = _get_env("HOST", "0.0.0.0")
    try:
        port = int(_get_env("PORT", "5000"))
    except Exception:
        port = 5000
    # 注意：根据用户要求，不在此处自动启动，只提供可运行入口
    app.run(host=host, port=port)