/*
 This file is part of GNU Taler
 (C) 2024 Taler Systems SA

 GNU Taler is free software; you can redistribute it and/or modify it under the
 terms of the GNU General Public License as published by the Free Software
 Foundation; either version 3, or (at your option) any later version.

 GNU Taler is distributed in the hope that it will be useful, but WITHOUT ANY
 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
 A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

 You should have received a copy of the GNU General Public License along with
 GNU Taler; see the file COPYING.  If not, see <http://www.gnu.org/licenses/>
 */

/**
 * @fileoverview Wrappers/proxies to make various interfaces observable.
 */

/**
 * Imports.
 */
import { IDBDatabase } from "@gnu-taler/idb-bridge";
import {
  ObservabilityContext,
  ObservabilityEventType,
} from "@gnu-taler/taler-util";
import { TaskIdStr } from "./common.js";
import { TalerCryptoInterface } from "./index.js";
import {
  DbAccess,
  DbReadOnlyTransaction,
  DbReadWriteTransaction,
  StoreNames,
} from "./query.js";
import { TaskScheduler } from "./shepherd.js";

/**
 * Task scheduler with extra observability events.
 */
export class ObservableTaskScheduler implements TaskScheduler {
  constructor(
    private impl: TaskScheduler,
    private oc: ObservabilityContext,
  ) {}

  private taskDepCache = new Set<string>();

  private declareDep(taskId: TaskIdStr): void {
    if (this.taskDepCache.size > 500) {
      this.taskDepCache.clear();
    }
    if (!this.taskDepCache.has(taskId)) {
      this.taskDepCache.add(taskId);
      this.oc.observe({
        type: ObservabilityEventType.DeclareTaskDependency,
        taskId,
      });
    }
  }

  shutdown(): Promise<void> {
    return this.impl.shutdown();
  }

  getActiveTasks(): TaskIdStr[] {
    return this.impl.getActiveTasks();
  }

  isIdle(): boolean {
    return this.impl.isIdle();
  }

  ensureRunning(): Promise<void> {
    return this.impl.ensureRunning();
  }

  startShepherdTask(taskId: TaskIdStr): void {
    this.declareDep(taskId);
    this.oc.observe({
      type: ObservabilityEventType.TaskStart,
      taskId,
    });
    return this.impl.startShepherdTask(taskId);
  }

  stopShepherdTask(taskId: TaskIdStr): void {
    this.declareDep(taskId);
    this.oc.observe({
      type: ObservabilityEventType.TaskStop,
      taskId,
    });
    return this.impl.stopShepherdTask(taskId);
  }

  resetTaskRetries(taskId: TaskIdStr): Promise<void> {
    this.declareDep(taskId);
    if (this.taskDepCache.size > 500) {
      this.taskDepCache.clear();
    }
    this.oc.observe({
      type: ObservabilityEventType.TaskReset,
      taskId,
    });
    return this.impl.resetTaskRetries(taskId);
  }

  async reload(): Promise<void> {
    return this.impl.reload();
  }
}

const locRegex = /\s*at\s*([a-zA-Z0-9_.!]*)\s*/;

export function getCallerInfo(up: number = 2): string {
  const stack = new Error().stack ?? "";
  const identifies: string[] = [];
  for (const line of stack.split("\n")) {
    let l = line.match(locRegex);
    if (l) {
      identifies.push(l[1]);
    }
  }
  return identifies.slice(up, up + 2).join("/");
}

export class ObservableDbAccess<StoreMap> implements DbAccess<StoreMap> {
  constructor(
    private impl: DbAccess<StoreMap>,
    private oc: ObservabilityContext,
  ) {}
  idbHandle(): IDBDatabase {
    return this.impl.idbHandle();
  }

  async runAllStoresReadWriteTx<T>(
    options: {
      label?: string;
    },
    txf: (
      tx: DbReadWriteTransaction<StoreMap, StoreNames<StoreMap>[]>,
    ) => Promise<T>,
  ): Promise<T> {
    const location = getCallerInfo();
    this.oc.observe({
      type: ObservabilityEventType.DbQueryStart,
      name: "<unknown>",
      location,
    });
    try {
      const ret = await this.impl.runAllStoresReadWriteTx(options, txf);
      this.oc.observe({
        type: ObservabilityEventType.DbQueryFinishSuccess,
        name: "<unknown>",
        location,
      });
      return ret;
    } catch (e) {
      this.oc.observe({
        type: ObservabilityEventType.DbQueryFinishError,
        name: "<unknown>",
        location,
      });
      throw e;
    }
  }

  async runAllStoresReadOnlyTx<T>(
    options: {
      label?: string;
    },
    txf: (
      tx: DbReadOnlyTransaction<StoreMap, StoreNames<StoreMap>[]>,
    ) => Promise<T>,
  ): Promise<T> {
    const location = getCallerInfo();
    this.oc.observe({
      type: ObservabilityEventType.DbQueryStart,
      name: options.label ?? "<unknown>",
      location,
    });
    try {
      const ret = await this.impl.runAllStoresReadOnlyTx(options, txf);
      this.oc.observe({
        type: ObservabilityEventType.DbQueryFinishSuccess,
        name: options.label ?? "<unknown>",
        location,
      });
      return ret;
    } catch (e) {
      this.oc.observe({
        type: ObservabilityEventType.DbQueryFinishError,
        name: options.label ?? "<unknown>",
        location,
      });
      throw e;
    }
  }

  async runReadWriteTx<T, StoreNameArray extends StoreNames<StoreMap>[]>(
    opts: {
      storeNames: StoreNameArray;
      label?: string;
    },
    txf: (tx: DbReadWriteTransaction<StoreMap, StoreNameArray>) => Promise<T>,
  ): Promise<T> {
    const location = getCallerInfo();
    this.oc.observe({
      type: ObservabilityEventType.DbQueryStart,
      name: opts.label ?? "<unknown>",
      location,
    });
    try {
      const ret = await this.impl.runReadWriteTx(opts, txf);
      this.oc.observe({
        type: ObservabilityEventType.DbQueryFinishSuccess,
        name: opts.label ?? "<unknown>",
        location,
      });
      return ret;
    } catch (e) {
      this.oc.observe({
        type: ObservabilityEventType.DbQueryFinishError,
        name: opts.label ?? "<unknown>",
        location,
      });
      throw e;
    }
  }

  async runReadOnlyTx<T, StoreNameArray extends StoreNames<StoreMap>[]>(
    opts: {
      storeNames: StoreNameArray;
      label?: string;
    },
    txf: (tx: DbReadOnlyTransaction<StoreMap, StoreNameArray>) => Promise<T>,
  ): Promise<T> {
    const location = getCallerInfo();
    try {
      this.oc.observe({
        type: ObservabilityEventType.DbQueryStart,
        name: opts.label ?? "<unknown>",
        location,
      });
      const ret = await this.impl.runReadOnlyTx(opts, txf);
      this.oc.observe({
        type: ObservabilityEventType.DbQueryFinishSuccess,
        name: opts.label ?? "<unknown>",
        location,
      });
      return ret;
    } catch (e) {
      this.oc.observe({
        type: ObservabilityEventType.DbQueryFinishError,
        name: opts.label ?? "<unknown>",
        location,
      });
      throw e;
    }
  }
}

export function observeTalerCrypto(
  impl: TalerCryptoInterface,
  oc: ObservabilityContext,
): TalerCryptoInterface {
  return Object.fromEntries(
    Object.keys(impl).map((name) => {
      return [
        name,
        async (req: any) => {
          oc.observe({
            type: ObservabilityEventType.CryptoStart,
            operation: name,
          });
          try {
            const res = await (impl as any)[name](req);
            oc.observe({
              type: ObservabilityEventType.CryptoFinishSuccess,
              operation: name,
            });
            return res;
          } catch (e) {
            oc.observe({
              type: ObservabilityEventType.CryptoFinishError,
              operation: name,
            });
            throw e;
          }
        },
      ];
    }),
  ) as any;
}