from __future__ import annotations

import json
import re
import urllib.error
import urllib.request
from datetime import datetime, timedelta, timezone
from typing import Any

from app.config import Settings
from app.db import Database, from_json, now_iso, to_json


UTC = timezone.utc


REQUIRED_ALERT_FIELDS = ("timeframe", "symbol", "strategy")
TEMPLATE_PATTERN = re.compile(r"{{\s*([a-zA-Z0-9_.-]+)\s*}}|(?<!{){\s*([a-zA-Z0-9_.-]+)\s*}(?!})")


class ValidationError(ValueError):
    pass


def normalize_alert(payload: dict[str, Any]) -> dict[str, Any]:
    missing = [field for field in REQUIRED_ALERT_FIELDS if not str(payload.get(field, "")).strip()]
    if missing:
        raise ValidationError(f"Missing required fields: {', '.join(missing)}")
    normalized = dict(payload)
    normalized["timeframe"] = str(payload["timeframe"]).strip()
    normalized["symbol"] = str(payload["symbol"]).strip().upper()
    normalized["strategy"] = str(payload["strategy"]).strip()
    if "price" in normalized and normalized["price"] not in (None, ""):
        try:
            normalized["price"] = float(normalized["price"])
        except (TypeError, ValueError) as exc:
            raise ValidationError("price must be numeric") from exc
    return normalized


def resolve_template_value(alert: dict[str, Any], field: str) -> str:
    value: Any = alert
    for part in field.split("."):
        if isinstance(value, dict) and part in value:
            value = value[part]
        else:
            return ""
    if value is None:
        return ""
    if isinstance(value, (dict, list)):
        return json.dumps(value, ensure_ascii=False)
    return str(value)


def render_template(template: str, alert: dict[str, Any]) -> str:
    return TEMPLATE_PATTERN.sub(lambda match: resolve_template_value(alert, match.group(1) or match.group(2)), template)


def default_body(alert: dict[str, Any]) -> str:
    action = alert.get("action") or alert.get("signal") or "alert"
    lines = [
        f"TradingView 信号: {alert['symbol']}",
        f"周期: {alert['timeframe']}",
        f"策略: {alert['strategy']}",
        f"动作: {action}",
    ]
    if alert.get("price") is not None:
        lines.append(f"价格: {alert['price']}")
    if alert.get("time"):
        lines.append(f"时间: {alert['time']}")
    return "\n".join(lines)


def build_feishu_message(alert: dict[str, Any], rule: dict[str, Any] | None = None) -> dict[str, Any]:
    rule = rule or {}
    title_template = rule.get("card_title_template") or "TradingView {{symbol}} {{action}}"
    body_template = rule.get("card_body_template") or default_body(alert)
    title = render_template(title_template, alert).strip() or f"TradingView {alert['symbol']}"
    body = render_template(body_template, alert).strip() or default_body(alert)

    if rule.get("message_type") == "text":
        return {"msg_type": "text", "content": {"text": f"{title}\n{body}"}}

    return {
        "msg_type": "interactive",
        "card": {
            "config": {"wide_screen_mode": True},
            "header": {
                "template": "blue",
                "title": {"tag": "plain_text", "content": title},
            },
            "elements": [
                {"tag": "div", "text": {"tag": "lark_md", "content": body}},
                {
                    "tag": "hr",
                },
                {
                    "tag": "note",
                    "elements": [
                        {
                            "tag": "plain_text",
                            "content": f"{alert['symbol']} · {alert['timeframe']} · {alert['strategy']}",
                        }
                    ],
                },
            ],
        },
    }


class Dispatcher:
    def __init__(self, db: Database, settings: Settings):
        self.db = db
        self.settings = settings

    def receive_alert(self, payload: dict[str, Any]) -> dict[str, Any]:
        alert = normalize_alert(payload)
        created_at = now_iso()
        with self.db.connect() as conn:
            rule = conn.execute(
                """
                SELECT * FROM routing_rules
                WHERE enabled = 1
                  AND timeframe = ?
                  AND upper(symbol) = ?
                  AND strategy = ?
                ORDER BY priority ASC, id ASC
                LIMIT 1
                """,
                (alert["timeframe"], alert["symbol"], alert["strategy"]),
            ).fetchone()

            status = "matched" if rule else "unmatched"
            cur = conn.execute(
                """
                INSERT INTO alerts (
                    timeframe, symbol, strategy, action, price, payload,
                    matched_rule_id, status, error, created_at
                )
                VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
                """,
                (
                    alert["timeframe"],
                    alert["symbol"],
                    alert["strategy"],
                    alert.get("action") or alert.get("signal"),
                    alert.get("price"),
                    to_json(alert),
                    rule["id"] if rule else None,
                    status,
                    None if rule else "No enabled routing rule matched this alert.",
                    created_at,
                ),
            )
            alert_id = int(cur.lastrowid)

            delivery_ids: list[int] = []
            if rule:
                target_ids = from_json(rule["target_ids"], [])
                if target_ids:
                    placeholders = ",".join("?" for _ in target_ids)
                    targets = conn.execute(
                        f"SELECT * FROM webhook_targets WHERE enabled = 1 AND id IN ({placeholders})",
                        target_ids,
                    ).fetchall()
                    for target in targets:
                        delivery = conn.execute(
                            """
                            INSERT INTO deliveries (
                                alert_id, rule_id, target_id, target_name, webhook_url,
                                status, attempts, next_attempt_at, created_at, updated_at
                            )
                            VALUES (?, ?, ?, ?, ?, 'pending', 0, ?, ?, ?)
                            """,
                            (
                                alert_id,
                                rule["id"],
                                target["id"],
                                target["name"],
                                target["webhook_url"],
                                created_at,
                                created_at,
                                created_at,
                            ),
                        )
                        delivery_ids.append(int(delivery.lastrowid))

            if rule and not delivery_ids:
                conn.execute(
                    "UPDATE alerts SET status = ?, error = ? WHERE id = ?",
                    ("unmatched", "Matched rule has no enabled webhook targets.", alert_id),
                )

        self.process_due_deliveries()
        return {
            "alert_id": alert_id,
            "status": status,
            "matched_rule_id": rule["id"] if rule else None,
            "delivery_ids": delivery_ids,
        }

    def process_due_deliveries(self, limit: int = 25) -> int:
        now = now_iso()
        with self.db.connect() as conn:
            rows = conn.execute(
                """
                SELECT d.*, a.payload
                , r.message_type, r.card_title_template, r.card_body_template
                FROM deliveries d
                JOIN alerts a ON a.id = d.alert_id
                LEFT JOIN routing_rules r ON r.id = d.rule_id
                WHERE d.status IN ('pending', 'retry')
                  AND (d.next_attempt_at IS NULL OR d.next_attempt_at <= ?)
                ORDER BY d.created_at ASC
                LIMIT ?
                """,
                (now, limit),
            ).fetchall()

        processed = 0
        for row in rows:
            delivery = dict(row)
            payload = from_json(delivery["payload"], {})
            self._send_delivery(delivery, payload)
            processed += 1
        return processed

    def _send_delivery(self, delivery: dict[str, Any], alert: dict[str, Any]) -> None:
        attempts = int(delivery["attempts"]) + 1
        message = build_feishu_message(alert, delivery)
        encoded = json.dumps(message, ensure_ascii=False).encode()
        request = urllib.request.Request(
            delivery["webhook_url"],
            data=encoded,
            headers={"Content-Type": "application/json"},
            method="POST",
        )
        response_code: int | None = None
        response_body: str | None = None
        error: str | None = None
        status = "sent"

        try:
            with urllib.request.urlopen(request, timeout=self.settings.feishu_timeout_seconds) as response:
                response_code = response.getcode()
                response_body = response.read(2048).decode(errors="replace")
                if response_code >= 400:
                    status = "failed"
                    error = f"Feishu webhook returned HTTP {response_code}"
        except urllib.error.HTTPError as exc:
            response_code = exc.code
            response_body = exc.read(2048).decode(errors="replace")
            status = "failed"
            error = f"Feishu webhook returned HTTP {exc.code}"
        except Exception as exc:
            status = "failed"
            error = str(exc)

        next_attempt_at = None
        if status == "failed" and attempts < self.settings.max_delivery_attempts:
            status = "retry"
            next_time = datetime.now(UTC) + timedelta(seconds=self.settings.retry_backoff_seconds * attempts)
            next_attempt_at = next_time.replace(microsecond=0).isoformat()

        with self.db.connect() as conn:
            conn.execute(
                """
                UPDATE deliveries
                SET status = ?, attempts = ?, next_attempt_at = ?, last_attempt_at = ?,
                    response_code = ?, response_body = ?, error = ?, updated_at = ?
                WHERE id = ?
                """,
                (
                    status,
                    attempts,
                    next_attempt_at,
                    now_iso(),
                    response_code,
                    response_body,
                    error,
                    now_iso(),
                    delivery["id"],
                ),
            )
            failed_open = conn.execute(
                """
                SELECT COUNT(*) AS count
                FROM deliveries
                WHERE alert_id = ? AND status IN ('pending', 'retry', 'failed')
                """,
                (delivery["alert_id"],),
            ).fetchone()["count"]
            conn.execute(
                "UPDATE alerts SET status = ? WHERE id = ?",
                ("delivered" if failed_open == 0 else "partial", delivery["alert_id"]),
            )