import fs from "node:fs";
import assert from "node:assert";
import { addAdditionalFilesToBuild } from "@trigger.dev/build/internal";
import { BuildManifest } from "@trigger.dev/core/v3";
import { BuildContext, BuildExtension } from "@trigger.dev/core/v3/build";

export type PythonOptions = {
  requirements?: string[];
  requirementsFile?: string;
  /**
   * [Dev-only] The path to the python binary.
   *
   * @remarks
   * This option is typically used during local development or in specific testing environments
   * where a particular Python installation needs to be targeted.  It should point to the full path of the python executable.
   *
   * Example: `/usr/bin/python3` or `C:\\Python39\\python.exe`
   */
  devPythonBinaryPath?: string;
  /**
   * An array of glob patterns that specify which Python scripts are allowed to be executed.
   *
   * @remarks
   * These scripts will be copied to the container during the build process.
   */
  scripts?: string[];
};

const splitAndCleanComments = (str: string) =>
  str
    .split("\n")
    .map((line) => line.trim())
    .filter((line) => line && !line.startsWith("#"));

export function pythonExtension(options: PythonOptions = {}): BuildExtension {
  return new PythonExtension(options);
}

class PythonExtension implements BuildExtension {
  public readonly name = "PythonExtension";

  constructor(private options: PythonOptions = {}) {
    assert(
      !(this.options.requirements && this.options.requirementsFile),
      "Cannot specify both requirements and requirementsFile"
    );

    if (this.options.requirementsFile) {
      assert(
        fs.existsSync(this.options.requirementsFile),
        `Requirements file not found: ${this.options.requirementsFile}`
      );
      this.options.requirements = splitAndCleanComments(
        fs.readFileSync(this.options.requirementsFile, "utf-8")
      );
    }
  }

  async onBuildComplete(context: BuildContext, manifest: BuildManifest) {
    await addAdditionalFilesToBuild(
      "pythonExtension",
      {
        files: this.options.scripts ?? [],
      },
      context,
      manifest
    );

    if (context.target === "dev") {
      if (this.options.devPythonBinaryPath) {
        process.env.PYTHON_BIN_PATH = this.options.devPythonBinaryPath;
      }

      return;
    }

    context.logger.debug(`Adding ${this.name} to the build`);

    context.addLayer({
      id: "python-installation",
      image: {
        instructions: splitAndCleanComments(`
          # Install Python
          RUN apt-get update && apt-get install -y --no-install-recommends \
              python3 python3-pip python3-venv && \
              apt-get clean && rm -rf /var/lib/apt/lists/*

          # Set up Python environment
          RUN python3 -m venv /opt/venv
          ENV PATH="/opt/venv/bin:$PATH"
        `),
      },
      deploy: {
        env: {
          PYTHON_BIN_PATH: `/opt/venv/bin/python`,
        },
        override: true,
      },
    });

    if (this.options.requirementsFile) {
      if (this.options.requirements) {
        context.logger.warn(
          `[pythonExtension] Both options.requirements and options.requirementsFile are specified. requirements will be ignored.`
        );
      }

      // Copy requirements file to the container
      await addAdditionalFilesToBuild(
        "pythonExtension",
        {
          files: [this.options.requirementsFile],
        },
        context,
        manifest
      );

      // Add a layer to the build that installs the requirements
      context.addLayer({
        id: "python-dependencies",
        image: {
          instructions: splitAndCleanComments(`
            # Copy the requirements file
            COPY ${this.options.requirementsFile} .
            # Install dependencies
            RUN pip install --no-cache-dir -r ${this.options.requirementsFile}
          `),
        },
        deploy: {
          override: true,
        },
      });
    } else if (this.options.requirements) {
      context.addLayer({
        id: "python-dependencies",
        build: {
          env: {
            REQUIREMENTS_CONTENT: this.options.requirements?.join("\n") || "",
          },
        },
        image: {
          instructions: splitAndCleanComments(`
          ARG REQUIREMENTS_CONTENT
          RUN echo "$REQUIREMENTS_CONTENT" > requirements.txt

          # Install dependencies
          RUN pip install --no-cache-dir -r requirements.txt
        `),
        },
        deploy: {
          override: true,
        },
      });
    }
  }
}