/**
 * Copyright (c) OpenLens Authors. All rights reserved.
 * Licensed under MIT License. See LICENSE in root directory for more information.
 */
import type { EnvironmentVariables } from "./compute-shell-environment.injectable";
import { getInjectable } from "@ogre-tools/injectable";
import getBasenameOfPathInjectable from "../../../common/path/get-basename.injectable";
import spawnInjectable from "../../child-process/spawn.injectable";
import randomUUIDInjectable from "../../crypto/random-uuid.injectable";
import loggerInjectable from "../../../common/logger.injectable";
import processExecPathInjectable from "./execPath.injectable";
import processEnvInjectable from "./env.injectable";
import { object } from "../../../common/utils";
import type { AsyncResult } from "../../../common/utils/async-result";

export interface UnixShellEnvOptions {
  signal: AbortSignal;
}

export type ComputeUnixShellEnvironment = (shell: string, opts: UnixShellEnvOptions) => Promise<AsyncResult<EnvironmentVariables, string>>;

/**
 * @param src The object containing the current environment variables
 * @param overrides The environment variables that want to be overridden before passing the env to a child process
 * @returns The combination of environment variables and a function which resets an object of environment variables to the values the keys corresponded to in `src` (rather than `overrides`)
 */
const getResetProcessEnv = (src: Partial<Record<string, string>>, overrides: Partial<Record<string, string>>): {
  resetEnvPairs: (target: Partial<Record<string, string>>) => void;
  env: Partial<Record<string, string>>;
} => {
  const originals = object.entries(overrides).map(([name]) => [name, src[name]] as const);

  return {
    env: {
      ...src,
      ...overrides,
    },
    resetEnvPairs: (target) => {
      for (const [name, orginalValue] of originals) {
        if (typeof orginalValue === "string") {
          target[name] = orginalValue;
        } else {
          delete target[name];
        }
      }
    },
  };
};

const computeUnixShellEnvironmentInjectable = getInjectable({
  id: "compute-unix-shell-environment",
  instantiate: (di): ComputeUnixShellEnvironment => {
    const powerShellName = /^pwsh(-preview)?$/;
    const cshLikeShellName = /^(t?csh)$/;
    const fishLikeShellName = /^fish$/;

    const getBasenameOfPath = di.inject(getBasenameOfPathInjectable);
    const spawn = di.inject(spawnInjectable);
    const logger = di.inject(loggerInjectable);
    const randomUUID = di.inject(randomUUIDInjectable);
    const processExecPath = di.inject(processExecPathInjectable);
    const processEnv = di.inject(processEnvInjectable);

    const getShellSpecifices = (shellName: string) => {
      const mark = randomUUID().replace(/-/g, "");
      const regex = new RegExp(`${mark}(\\{.*\\})${mark}`);

      if (powerShellName.test(shellName)) {
        // Older versions of PowerShell removes double quotes sometimes so we use "double single quotes" which is how
        // you escape single quotes inside of a single quoted string.
        return {
          command: `Command '${processExecPath}' -p '\\"${mark}\\" + JSON.stringify(process.env) + \\"${mark}\\"'`,
          shellArgs: ["-Login"],
          regex,
        };
      }

      let command = `'${processExecPath}' -p '"${mark}" + JSON.stringify(process.env) + "${mark}"'`;
      const shellArgs = ["-l"];

      if (fishLikeShellName.test(shellName)) {
        shellArgs.push("-c", command);
        command = "";
      } else if (!cshLikeShellName.test(shellName)) {
        // zsh (at least, maybe others) don't load RC files when in non-interactive mode, even when using -l (login) option
        shellArgs.push("-i");
      } else {
        // Some shells don't support any other options when providing the -l (login) shell option
      }

      return { command, shellArgs, regex };
    };


    return async (shellPath, opts) => {
      const { resetEnvPairs, env } = getResetProcessEnv(processEnv, {
        ELECTRON_RUN_AS_NODE: "1",
        ELECTRON_NO_ATTACH_CONSOLE: "1",
        TERM: "screen-256color-bce", // required for fish
      });
      const shellName = getBasenameOfPath(shellPath);
      const { command, shellArgs, regex } = getShellSpecifices(shellName);

      logger.info(`[UNIX-SHELL-ENV]: running against ${shellPath}`, { command, shellArgs });

      return new Promise((resolve) => {
        const shellProcess = spawn(shellPath, shellArgs, {
          signal: opts.signal,
          detached: true,
          env,
        });
        const stdout: Buffer[] = [];
        const stderr: Buffer[] = [];

        const getErrorContext = (other: object = {}) => {
          const context = {
            ...other,
            stdout: Buffer.concat(stdout).toString("utf-8"),
            stderr: Buffer.concat(stderr).toString("utf-8"),
          };

          return JSON.stringify(context, null, 4);
        };

        shellProcess.stdout.on("data", b => stdout.push(b));
        shellProcess.stderr.on("data", b => stderr.push(b));

        shellProcess.on("error", (error) => {
          if (opts.signal.aborted) {
            resolve({
              callWasSuccessful: false,
              error: `timeout: ${getErrorContext()}`,
            });
          } else {
            resolve({
              callWasSuccessful: false,
              error: `Failed to spawn ${shellPath}: ${getErrorContext({ error: String(error) })}`,
            });
          }
        });
        shellProcess.on("close", (code, signal) => {
          if (code || signal) {
            return resolve({
              callWasSuccessful: false,
              error: `Shell did not exit sucessfully: ${getErrorContext({ code, signal })}`,
            });
          }

          try {
            const rawOutput = Buffer.concat(stdout).toString("utf-8");

            logger.info(`[UNIX-SHELL-ENV]: got the following output`, { rawOutput });

            const match = regex.exec(rawOutput);
            const strippedRawOutput = match ? match[1] : "{}";
            const resolvedEnv = JSON.parse(strippedRawOutput) as Partial<Record<string, string>>;

            resetEnvPairs(resolvedEnv);
            resolve({
              callWasSuccessful: true,
              response: resolvedEnv,
            });
          } catch (err) {
            resolve({
              callWasSuccessful: false,
              error: String(err),
            });
          }
        });

        shellProcess.stdin.end(command);
      });
    };
  },
  causesSideEffects: true,
});

export default computeUnixShellEnvironmentInjectable;