/**
 * Regenerates the translations base file by walking the source tree and
 * parsing each file with flow-parser. Emits a JSON file with the
 * translatable strings mapped to themselves in the order they appeared
 * in the files and grouped by the file they appeared in.
 *
 * Usage: node scripts/gen-i18n.js
 */
const fs = require('fs');
const path = require('path');

const walk = require('walk');

const flowParser = require('flow-parser');
const estreeWalker = require('estree-walker');

const TRANSLATIONS_FUNCS = ['_t', '_td', '_tJsx'];

// A selection of plural variants to put in the base file: other langauges
// with more types of plural will have more, but they will just be in the file
// for that language.
const COUNTSTRINGS = ['one', 'other'];

const FLOW_PARSER_OPTS = {
  esproposal_class_instance_fields: true,
  esproposal_class_static_fields: true,
  esproposal_decorators: true,
  esproposal_export_star_as: true,
  types: true,
};

function getObjectValue(obj, key) {
    for (const prop of obj.properties) {
        if (prop.key.type == 'Identifier' && prop.key.name == key) {
            return prop.value;
        }
    }
    return null;
}

function getTKey(arg) {
    if (arg.type == 'Literal') {
        return arg.value;
    } else if (arg.type == 'BinaryExpression' && arg.operator == '+') {
        return getTKey(arg.left) + getTKey(arg.right);
    } else if (arg.type == 'TemplateLiteral') {
        return arg.quasis.map((q) => {
            return q.value.raw;
        }).join('');
    }
    return null;
}

function getTranslations(file) {
    const tree = flowParser.parse(fs.readFileSync(file, { encoding: 'utf8' }), FLOW_PARSER_OPTS)

    const trs = new Set();

    estreeWalker.walk(tree, {
        enter: function(node, parent) {
            //console.log(node);
            if (
                node.type == 'CallExpression' &&
                TRANSLATIONS_FUNCS.includes(node.callee.name)
            ) {
                const tKey = getTKey(node.arguments[0]);
                if (tKey === null) return;

                let isPlural = false;
                if (node.arguments.length > 1 && node.arguments[1].type == 'ObjectExpression') {
                    const countVal = getObjectValue(node.arguments[1], 'count');
                    if (countVal) {
                        isPlural = true;
                    }
                }

                if (isPlural) {
                    for (const s of COUNTSTRINGS) {
                        trs.add(tKey + "|" + s);
                    }
                } else {
                    trs.add(tKey);
                }
            }
        }
    });

    return trs;
}

const translatables = new Set();

walk.walkSync("src", {
    listeners: {
        file: function(root, fileStats, next) {
            if (!fileStats.name.endsWith('.js')) return;

            const fullPath = path.join(root, fileStats.name);
            const trs = getTranslations(fullPath);
            console.log(`${fullPath} (${trs.size} strings)`);
            for (const tr of trs.values()) {
                translatables.add(tr);
            }
        },
    }
});

const trObj = {};
for (const tr of translatables) {
    trObj[tr] = tr;
}

fs.writeFileSync(
    "src/i18n/strings/en_EN.json",
    JSON.stringify(trObj, translatables.values(), 4) + "\n"
);