"""System error log storage."""

from __future__ import annotations

import hashlib
import json
import os
import socket
import traceback
from datetime import datetime, timedelta

from app.db.schema import get_conn


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


def _truncate(value, limit: int) -> str:
    text = str(value or "")
    return text[:limit]


def _json(value) -> str:
    try:
        return json.dumps(value or {}, ensure_ascii=False, default=str)
    except Exception:
        return "{}"


def _fingerprint(error_type: str, message: str, stack_trace: str, path: str = "") -> str:
    basis = "\n".join([
        str(error_type or ""),
        str(message or "")[:500],
        str(path or ""),
        str(stack_trace or "").splitlines()[-12:][0] if stack_trace else "",
    ])
    return hashlib.sha256(basis.encode("utf-8", errors="ignore")).hexdigest()[:32]


def record_system_error(
    *,
    source: str,
    level: str = "error",
    message: str = "",
    error_type: str = "",
    stack_trace: str = "",
    request_method: str = "",
    request_path: str = "",
    query_string: str = "",
    user_email: str = "",
    user_id: int = 0,
    status_code: int = 500,
    context: dict | None = None,
    fingerprint: str = "",
) -> int:
    """Persist a system error. Logging must never raise into the caller."""
    try:
        error_type = error_type or "Error"
        stack_trace = stack_trace or ""
        fingerprint = fingerprint or _fingerprint(error_type, message, stack_trace, request_path)
        conn = get_conn()
        try:
            row = conn.execute(
                """
                INSERT INTO system_error_log (
                    created_at, level, source, error_type, message, stack_trace,
                    request_method, request_path, query_string, user_email, user_id,
                    status_code, fingerprint, context_json, host, pid
                ) VALUES (%s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s, %s)
                RETURNING id
                """,
                (
                    _now(),
                    _truncate(level or "error", 20),
                    _truncate(source or "app", 80),
                    _truncate(error_type, 160),
                    _truncate(message, 2000),
                    _truncate(stack_trace, 60000),
                    _truncate(request_method, 16),
                    _truncate(request_path, 500),
                    _truncate(query_string, 1000),
                    _truncate(user_email, 255),
                    int(user_id or 0),
                    int(status_code or 0),
                    fingerprint,
                    _json(context),
                    _truncate(socket.gethostname(), 120),
                    int(os.getpid() or 0),
                ),
            )
            log_id = row.fetchone()["id"]
            conn.commit()
            return int(log_id)
        finally:
            conn.close()
    except Exception:
        return 0


def record_exception(exc: BaseException, *, source: str, context: dict | None = None, **kwargs) -> int:
    return record_system_error(
        source=source,
        error_type=exc.__class__.__name__,
        message=str(exc),
        stack_trace="".join(traceback.format_exception(type(exc), exc, exc.__traceback__)),
        context=context or {},
        **kwargs,
    )


def list_system_errors(
    *,
    offset: int = 0,
    limit: int = 50,
    level: str = "",
    source: str = "",
    search: str = "",
    hours: int = 168,
) -> dict:
    limit = max(1, min(int(limit or 50), 200))
    offset = max(0, int(offset or 0))
    where = []
    params = []
    if level and level != "all":
        where.append("level=%s")
        params.append(level)
    if source and source != "all":
        where.append("source=%s")
        params.append(source)
    if search:
        like = f"%{search.strip()}%"
        where.append("(message ILIKE %s OR error_type ILIKE %s OR request_path ILIKE %s OR user_email ILIKE %s)")
        params.extend([like, like, like, like])
    if hours and int(hours) > 0:
        cutoff = (datetime.now() - timedelta(hours=int(hours))).isoformat()
        where.append("created_at >= %s")
        params.append(cutoff)
    clause = "WHERE " + " AND ".join(where) if where else ""
    conn = get_conn()
    try:
        total = conn.execute(f"SELECT COUNT(*) AS n FROM system_error_log {clause}", tuple(params)).fetchone()["n"]
        rows = conn.execute(
            f"""
            SELECT id, created_at, level, source, error_type, message, request_method,
                   request_path, user_email, user_id, status_code, fingerprint, host, pid
            FROM system_error_log
            {clause}
            ORDER BY id DESC
            LIMIT %s OFFSET %s
            """,
            tuple(params + [limit, offset]),
        ).fetchall()
        return {
            "items": [dict(row) for row in rows],
            "total": int(total or 0),
            "limit": limit,
            "offset": offset,
            "has_more": offset + limit < int(total or 0),
        }
    finally:
        conn.close()


def get_system_error(log_id: int) -> dict | None:
    conn = get_conn()
    try:
        row = conn.execute("SELECT * FROM system_error_log WHERE id=%s", (int(log_id),)).fetchone()
        if not row:
            return None
        item = dict(row)
        try:
            item["context"] = json.loads(item.get("context_json") or "{}")
        except Exception:
            item["context"] = {}
        return item
    finally:
        conn.close()


def get_system_error_stats(hours: int = 24) -> dict:
    cutoff = (datetime.now() - timedelta(hours=int(hours or 24))).isoformat()
    conn = get_conn()
    try:
        rows = conn.execute(
            """
            SELECT level, source, COUNT(*) AS n
            FROM system_error_log
            WHERE created_at >= %s
            GROUP BY level, source
            ORDER BY n DESC
            """,
            (cutoff,),
        ).fetchall()
        latest = conn.execute(
            """
            SELECT created_at, level, source, error_type, message
            FROM system_error_log
            ORDER BY id DESC LIMIT 1
            """
        ).fetchone()
        return {
            "hours": int(hours or 24),
            "total": sum(int(row["n"] or 0) for row in rows),
            "groups": [dict(row) for row in rows],
            "latest": dict(latest) if latest else None,
        }
    finally:
        conn.close()