/** @file Configuration for the esbuild bundler and build/watch commands.
 *
 * The bundler processes each entry point into a single file, each with no external dependencies and
 * minified. This primarily involves resolving all imports, along with some other transformations
 * (like TypeScript compilation).
 *
 * See the bundlers documentation for more information:
 * https://esbuild.github.io/getting-started/#bundling-for-node. */
import * as fs from 'node:fs/promises'
import * as path from 'node:path'
import * as url from 'node:url'

import type * as esbuild from 'esbuild'
import * as esbuildPluginNodeModules from '@esbuild-plugins/node-modules-polyfill'
import esbuildPluginInlineImage from 'esbuild-plugin-inline-image'
import esbuildPluginTime from 'esbuild-plugin-time'
import esbuildPluginYaml from 'esbuild-plugin-yaml'

import postcss from 'postcss'
import tailwindcss from 'tailwindcss'
import tailwindcssNesting from 'tailwindcss/nesting/index.js'

import * as tailwindConfig from './tailwind.config'
import * as utils from '../../utils'

// =================
// === Constants ===
// =================

const THIS_PATH = path.resolve(path.dirname(url.fileURLToPath(import.meta.url)))

// =============================
// === Environment variables ===
// =============================

/** Mandatory build options. */
export interface Arguments {
    /** Path where bundled files are output. */
    outputPath: string
    /** `true` if in development mode (live-reload), `false` if in production mode. */
    devMode: boolean
}

/** Get arguments from the environment. */
export function argumentsFromEnv(): Arguments {
    const outputPath = path.resolve(utils.requireEnv('ENSO_BUILD_GUI'), 'assets')
    return { outputPath, devMode: false }
}

// =======================
// === Esbuild plugins ===
// =======================

/** A plugin to process all CSS files with Tailwind CSS. */
export function esbuildPluginGenerateTailwind(): esbuild.Plugin {
    return {
        name: 'enso-generate-tailwind',
        setup: build => {
            const cssProcessor = postcss([
                tailwindcss({
                    config: tailwindConfig,
                }),
                tailwindcssNesting(),
            ])
            build.onLoad({ filter: /tailwind\.css$/ }, async loadArgs => {
                // console.log(`Processing CSS file '${loadArgs.path}'.`)
                const content = await fs.readFile(loadArgs.path, 'utf8')
                const result = await cssProcessor.process(content, { from: loadArgs.path })
                // console.log(`Processed CSS file '${loadArgs.path}'.`)
                return {
                    contents: result.content,
                    loader: 'css',
                    watchFiles: [loadArgs.path],
                }
            })
        },
    }
}

// ================
// === Bundling ===
// ================

/** Generate the bundler options. */
export function bundlerOptions(args: Arguments) {
    const { outputPath, devMode } = args
    // This is required to prevent TypeScript from narrowing `true` to `boolean`.
    // eslint-disable-next-line no-restricted-syntax
    const trueBoolean = true as boolean
    const buildOptions = {
        absWorkingDir: THIS_PATH,
        bundle: trueBoolean,
        entryPoints: [path.resolve(THIS_PATH, 'src', 'tailwind.css')],
        outdir: outputPath,
        outbase: 'src',
        loader: {
            /* eslint-disable @typescript-eslint/naming-convention */
            // The `file` loader copies the file, and replaces the import with the path to the file.
            '.png': 'file',
            /* eslint-enable @typescript-eslint/naming-convention */
        },
        plugins: [
            // The CSS file needs to import a single SVG as a data URL.
            // For `bundle.ts` and `watch.ts`, `index.js` also includes various SVG icons
            // which need to be bundled.
            // Depending on file size, choose between `dataurl` and `file` loaders.
            // The `dataurl` loader replaces the import with the file, as a data URL. Using the
            // `file` loader, which copies the file and replaces the import with the path.
            /* eslint-disable @typescript-eslint/naming-convention */
            esbuildPluginInlineImage({ extensions: ['svg'] }),
            esbuildPluginNodeModules.NodeModulesPolyfillPlugin(),
            esbuildPluginTime(),
            // This is not strictly needed because the cloud frontend does not use
            // the Project Manager, however it is very difficult to conditionally exclude a module.
            esbuildPluginYaml.yamlPlugin({}),
            esbuildPluginGenerateTailwind(),
        ],
        define: {
            // We are defining constants, so it should be `CONSTANT_CASE`.
            /* eslint-disable @typescript-eslint/naming-convention */
            /** Whether the application is being run locally. This enables a service worker that
             * properly serves `/index.html` to client-side routes like `/login`. */
            'process.env.NODE_ENV': JSON.stringify(devMode ? 'development' : 'production'),
            /** Overrides the redirect URL for OAuth logins in the production environment.
             * This is needed for logins to work correctly under `./run gui watch`. */
            REDIRECT_OVERRIDE: 'undefined',
            CLOUD_ENV:
                process.env.ENSO_CLOUD_ENV != null
                    ? JSON.stringify(process.env.ENSO_CLOUD_ENV)
                    : 'undefined',
            /* eslint-enable @typescript-eslint/naming-convention */
        },
        pure: ['assert'],
        sourcemap: true,
        minify: !devMode,
        metafile: trueBoolean,
        format: 'esm',
        platform: 'browser',
        color: trueBoolean,
    } satisfies esbuild.BuildOptions
    // The narrower type is required to avoid non-null assertions elsewhere.
    // The intersection with `esbuild.BuildOptions` is required to allow adding extra properties.
    const correctlyTypedBuildOptions: esbuild.BuildOptions & typeof buildOptions = buildOptions
    return correctlyTypedBuildOptions
}

/** esbuild options for bundling (one-off build) the package.
 *
 * Relies on the environment variables to be set. */
export function bundleOptions() {
    return bundlerOptions(argumentsFromEnv())
}