import { File } from "../../core/File";

/**
 * Handles require and ImportDeclarations
 * At the moment does not transpile
 */
export class ImportDeclaration {

    /**
     * Extract require statements
     * At the same time replace aliases
     */
    public static onNode(file: File, node: any, parent: any) {
        const analysis = file.analysis;
        if (node.type === "CallExpression" && node.callee) {
            if (node.callee.type === "Identifier" && node.callee.name === "require") {
                let arg1 = node.arguments[0];
                if (analysis.nodeIsString(arg1)) {
                    let requireStatement = this.handleAliasReplacement(file, arg1.value);
                    arg1.value = requireStatement;
                    analysis.addDependency(requireStatement);
                }
            }
        }
        if (node.type === "ExportAllDeclaration") {
            file.es6module = true;
            analysis.addDependency(node.source.value);
        }

        if (node.type === "ImportDeclaration" || node.type === "ExportNamedDeclaration") {
            if (!file.context.rollupOptions) {
                file.es6module = true;
            }
            if (node.source && analysis.nodeIsString(node.source)) {
                let requireStatement = this.handleAliasReplacement(file, node.source.value);
                node.source.value = requireStatement;
                analysis.addDependency(requireStatement);
            }
        }
    }

    public static onEnd(file: File) {
        // We detect that imports are used
        // Now we need to transpile the code
        if (file.es6module) {
            file.context.log.magicReason(
                'used typescript to compile because an import was used',
                file.info.fuseBoxPath)

            const ts = require("typescript");
            let tsconfg: any = {
                compilerOptions: {
                    module: "commonjs",
                    target: "es5"
                },
            };;
            let result = ts.transpileModule(file.contents, tsconfg);
            file.contents = result.outputText;
        }
    }

    /**
     * Replace aliases using the context collection
     */
    private static handleAliasReplacement(file: File, requireStatement: string): string {

        // checking for browser override (asap) case
        // these people ...
        // https://github.com/defunctzombie/package-browser-field-spec
        if (file.collection && file.collection.info && file.collection.info.browserOverrides) {
            const overrides = file.collection.info.browserOverrides;
            if (overrides) {
                //require statement without file ext and override with ext
                let requireStatementWithExt = requireStatement + '.js';
                if (overrides[requireStatement] || overrides[requireStatementWithExt]) {
                    requireStatement = overrides[requireStatement] || overrides[requireStatementWithExt];
                    file.analysis.requiresRegeneration = true;
                }
            }
        }

        if (!file.context.experimentalAliasEnabled) {
            return requireStatement;
        }
        const aliasCollection = file.context.aliasCollection;
        aliasCollection.forEach(props => {
            if (props.expr.test(requireStatement)) {
                requireStatement = requireStatement.replace(props.expr, `${props.replacement}$2`);
                // only if we need it
                file.analysis.requiresRegeneration = true;
            }
        });
        return requireStatement;
    }
}