import { Database } from "bun:sqlite";
import { mkdirSync as fsMkdirSync } from "node:fs";
import { dirname } from "node:path";
import type { CheckFailure, ResolvedTarget, StoredCheckResult, StoredTarget } from "./types";

const CREATE_TARGETS_TABLE = `
CREATE TABLE IF NOT EXISTS targets (
  id INTEGER PRIMARY KEY AUTOINCREMENT,
  name TEXT NOT NULL UNIQUE,
  type TEXT NOT NULL,
  target TEXT NOT NULL,
  config TEXT NOT NULL DEFAULT '{}',
  interval_ms INTEGER NOT NULL,
  timeout_ms INTEGER NOT NULL,
  expect TEXT,
  grp TEXT NOT NULL DEFAULT 'default'
)
`;

const CREATE_CHECK_RESULTS_TABLE = `
CREATE TABLE IF NOT EXISTS check_results (
  id INTEGER PRIMARY KEY AUTOINCREMENT,
  target_id INTEGER NOT NULL,
  timestamp TEXT NOT NULL,
  matched INTEGER NOT NULL,
  duration_ms REAL,
  status_detail TEXT,
  failure TEXT,
  FOREIGN KEY (target_id) REFERENCES targets(id)
)
`;

const CREATE_INDEX = `
CREATE INDEX IF NOT EXISTS idx_check_results_target_timestamp
ON check_results (target_id, timestamp)
`;

export class ProbeStore {
  private db: Database;
  private closed = false;

  constructor(dbPath: string) {
    ensureDir(dirname(dbPath));
    this.db = new Database(dbPath, { create: true });
    this.db.run("PRAGMA journal_mode = WAL");
    this.db.run(CREATE_TARGETS_TABLE);
    this.db.run(CREATE_CHECK_RESULTS_TABLE);
    this.db.run(CREATE_INDEX);
  }

  syncTargets(targets: ResolvedTarget[]): void {
    if (this.closed) return;
    const existingRows = this.db.query("SELECT id, name FROM targets").all() as Array<{
      id: number;
      name: string;
    }>;
    const existingMap = new Map(existingRows.map((r) => [r.name, r.id]));
    const configNames = new Set(targets.map((t) => t.name));

    const insertStmt = this.db.prepare(
      "INSERT INTO targets (name, type, target, config, interval_ms, timeout_ms, expect, grp) VALUES (?, ?, ?, ?, ?, ?, ?, ?)",
    );
    const updateStmt = this.db.prepare(
      "UPDATE targets SET type = ?, target = ?, config = ?, interval_ms = ?, timeout_ms = ?, expect = ?, grp = ? WHERE id = ?",
    );
    const deleteStmt = this.db.prepare("DELETE FROM targets WHERE id = ?");

    const tx = this.db.transaction(() => {
      for (const t of targets) {
        const type = t.type;
        const target = buildTargetDisplay(t);
        const config = buildTargetConfig(t);
        const expect = t.expect ? JSON.stringify(t.expect) : null;

        if (existingMap.has(t.name)) {
          updateStmt.run(type, target, config, t.intervalMs, t.timeoutMs, expect, t.group, existingMap.get(t.name)!);
        } else {
          insertStmt.run(t.name, type, target, config, t.intervalMs, t.timeoutMs, expect, t.group);
        }
      }

      for (const [name, id] of existingMap) {
        if (!configNames.has(name)) {
          deleteStmt.run(id);
        }
      }
    });

    tx();
  }

  getTargets(): StoredTarget[] {
    if (this.closed) return [];
    return this.db
      .query("SELECT * FROM targets ORDER BY CASE WHEN grp='default' THEN 0 ELSE 1 END, id")
      .all() as StoredTarget[];
  }

  getTargetById(id: number): StoredTarget | null {
    if (this.closed) return null;
    return this.db.query("SELECT * FROM targets WHERE id = ?").get(id) as StoredTarget | null;
  }

  insertCheckResult(result: {
    targetId: number;
    timestamp: string;
    matched: boolean;
    durationMs: number | null;
    statusDetail: string | null;
    failure: CheckFailure | null;
  }): void {
    if (this.closed) return;
    this.db
      .prepare(
        "INSERT INTO check_results (target_id, timestamp, matched, duration_ms, status_detail, failure) VALUES (?, ?, ?, ?, ?, ?)",
      )
      .run(
        result.targetId,
        result.timestamp,
        result.matched ? 1 : 0,
        result.durationMs,
        result.statusDetail,
        result.failure ? JSON.stringify(result.failure) : null,
      );
  }

  getLatestCheck(targetId: number): StoredCheckResult | null {
    return this.db
      .query("SELECT * FROM check_results WHERE target_id = ? ORDER BY timestamp DESC LIMIT 1")
      .get(targetId) as StoredCheckResult | null;
  }

  getHistory(
    targetId: number,
    from: string,
    to: string,
    page = 1,
    pageSize = 20,
  ): { items: StoredCheckResult[]; total: number; page: number; pageSize: number } {
    const countRow = this.db
      .prepare("SELECT COUNT(*) as total FROM check_results WHERE target_id = ? AND timestamp >= ? AND timestamp <= ?")
      .get(targetId, from, to) as { total: number };

    const offset = (page - 1) * pageSize;
    const items = this.db
      .prepare(
        "SELECT * FROM check_results WHERE target_id = ? AND timestamp >= ? AND timestamp <= ? ORDER BY timestamp DESC LIMIT ? OFFSET ?",
      )
      .all(targetId, from, to, pageSize, offset) as StoredCheckResult[];

    return { items, total: countRow.total, page, pageSize };
  }

  getTargetStats(targetId: number): {
    totalChecks: number;
    availability: number;
  } {
    const row = this.db
      .prepare(
        `SELECT
          COUNT(*) as totalChecks,
          COALESCE(SUM(CASE WHEN matched = 1 THEN 1 ELSE 0 END), 0) as upCount
        FROM check_results
        WHERE target_id = ?`,
      )
      .get(targetId) as { totalChecks: number; upCount: number };

    const totalChecks = row.totalChecks;
    const availability = totalChecks > 0 ? (row.upCount / totalChecks) * 100 : 0;

    return {
      totalChecks,
      availability: Math.round(availability * 100) / 100,
    };
  }

  getTrend(
    targetId: number,
    from: string,
    to: string,
  ): Array<{
    hour: string;
    avgDurationMs: number | null;
    availability: number;
    totalChecks: number;
  }> {
    return this.db
      .prepare(
        `SELECT
          strftime('%Y-%m-%dT%H:00:00', timestamp) as hour,
          AVG(CASE WHEN matched = 1 THEN duration_ms END) as avgDurationMs,
          CASE WHEN COUNT(*) > 0 THEN (SUM(CASE WHEN matched = 1 THEN 1 ELSE 0 END) * 100.0 / COUNT(*)) ELSE 0 END as availability,
          COUNT(*) as totalChecks
        FROM check_results
        WHERE target_id = ? AND timestamp >= ? AND timestamp <= ?
        GROUP BY hour
        ORDER BY hour`,
      )
      .all(targetId, from, to) as Array<{
      hour: string;
      avgDurationMs: number | null;
      availability: number;
      totalChecks: number;
    }>;
  }

  getSummary(): {
    total: number;
    up: number;
    down: number;
    lastCheckTime: string | null;
  } {
    const targets = this.getTargets();
    let up = 0;
    let down = 0;
    let lastCheckTime: string | null = null;

    for (const target of targets) {
      const latest = this.getLatestCheck(target.id);

      if (latest) {
        if (latest.matched) {
          up++;
        } else {
          down++;
        }

        if (!lastCheckTime || latest.timestamp > lastCheckTime) {
          lastCheckTime = latest.timestamp;
        }
      } else {
        down++;
      }
    }

    return {
      total: targets.length,
      up,
      down,
      lastCheckTime,
    };
  }

  getRecentSamples(
    targetId: number,
    limit: number,
  ): Array<{ timestamp: string; duration_ms: number | null; matched: number }> {
    return this.db
      .prepare(
        "SELECT timestamp, duration_ms, matched FROM check_results WHERE target_id = ? ORDER BY timestamp DESC LIMIT ?",
      )
      .all(targetId, limit) as Array<{
      timestamp: string;
      duration_ms: number | null;
      matched: number;
    }>;
  }

  close(): void {
    this.closed = true;
    this.db.close();
  }
}

function buildTargetDisplay(t: ResolvedTarget): string {
  if (t.type === "http") {
    return t.http.url;
  }
  const parts = [t.command.exec, ...t.command.args];
  return `exec ${parts.join(" ")}`;
}

function buildTargetConfig(t: ResolvedTarget): string {
  if (t.type === "http") {
    return JSON.stringify({
      url: t.http.url,
      method: t.http.method,
      headers: t.http.headers,
      body: t.http.body,
      maxBodyBytes: t.http.maxBodyBytes,
    });
  }
  return JSON.stringify({
    exec: t.command.exec,
    args: t.command.args,
    cwd: t.command.cwd,
    env: t.command.env,
    maxOutputBytes: t.command.maxOutputBytes,
  });
}

function ensureDir(dir: string): void {
  try {
    fsMkdirSync(dir, { recursive: true });
  } catch {
    // already exists
  }
}