import fs from 'node:fs/promises';

import { deepListKeys } from '#shared/helpers.ts';
import { listMissingTranslations } from '#shared/missingTranslations.ts';
import { DictNode, parse } from '~/helpers/merge/sumlAst.ts';
import type { Node } from '~/helpers/merge/sumlAst.ts';
import type { Config } from '~~/locale/config.ts';
import type { Translations } from '~~/locale/translations.ts';
import { loadSuml } from '~~/server/loader.ts';
import { rootDir } from '~~/server/paths.ts';

export const loadDocument = async (name: string) => {
    return parse(await fs.readFile(`${rootDir}/${name}`, 'utf-8'));
};

export const saveDocument = async (name: string, document: Node) => {
    await fs.writeFile(`${rootDir}/${name}`, `${document.toString()}\n`);
};

export const mergeTranslationProposals = async (locale: string, proposalsFile: string) => {
    const baseTranslationsDocument = await loadDocument('locale/_base/translations.suml');
    const localeTranslationsDocument = await loadDocument(`locale/${locale}/translations.suml`);
    const proposalsDocument = await loadDocument(proposalsFile);

    if (!(proposalsDocument instanceof DictNode) ||
        !(baseTranslationsDocument instanceof DictNode) ||
        !(localeTranslationsDocument instanceof DictNode)) {
        throw new Error('input nodes must be DictNode');
    }

    merge(proposalsDocument, baseTranslationsDocument, localeTranslationsDocument);
    await saveDocument(`locale/${locale}/translations.suml`, localeTranslationsDocument);
};

export const merge = (source: DictNode, base: DictNode, target: DictNode) => {
    const baseKeys = base.items.map((entry) => entry.key);
    for (const sourceEntry of source.items) {
        const baseEntry = base.items.find((baseEntry) => baseEntry.key === sourceEntry.key);
        const targetEntry = target.items.find((targetEntry) => targetEntry.key === sourceEntry.key);
        if (targetEntry === undefined) {
            let insertIndex = 0;
            if (baseEntry === undefined) {
                insertIndex = target.items.length;
            } else {
                const baseIndex = baseKeys.indexOf(baseEntry.key);
                const previousKeys = baseKeys.slice(0, baseIndex).toReversed();
                for (const previousKey of previousKeys) {
                    const targetIndex = target.items.findIndex((targetEntry) => targetEntry.key === previousKey);
                    if (targetIndex !== -1) {
                        insertIndex = targetIndex + 1;
                        break;
                    }
                }
            }
            target.items.splice(insertIndex, 0, sourceEntry);
        } else if (targetEntry.value instanceof DictNode) {
            if (!(sourceEntry.value instanceof DictNode)) {
                throw new Error('source entry must be an DictNode when merging');
            }
            const childBase = baseEntry?.value instanceof DictNode ? baseEntry.value : new DictNode([], []);
            merge(sourceEntry.value, childBase, targetEntry.value);
        } else {
            targetEntry.value = sourceEntry.value;
        }
    }
};

export const createTranslationFiles = async (locale: string) => {
    const baseTranslations = await loadSuml<Translations>('locale/_base/translations.suml');
    const config = await loadSuml<Config>('locale/_base/config.suml');

    const configDocument = await loadDocument('locale/_base/config.suml');
    const translationsDocument = await loadDocument('locale/_base/translations.suml');

    const requiredTranslationKeys = listMissingTranslations({}, baseTranslations, config);
    for (const key of deepListKeys(baseTranslations)) {
        if (!requiredTranslationKeys.includes(key)) {
            remove(translationsDocument, key.split('.'));
        }
    }

    await fs.mkdir(`${rootDir}/locale/${locale}`, { recursive: true });
    await saveDocument(`locale/${locale}/config.suml`, configDocument);
    await saveDocument(`locale/${locale}/translations.suml`, translationsDocument);
};

export const remove = (node: Node, path: string[]) => {
    if (!(node instanceof DictNode)) {
        throw new Error('node must be DictNode');
    }

    if (path.length === 1) {
        node.items = node.items.filter((item) => item.key !== path[0]);
        return;
    }
    const childNode = node.items.find((item) => item.key === path[0])?.value;
    if (!childNode) {
        return;
    }
    remove(childNode, path.slice(1));
    node.items = node.items.filter((item) => !(item.value instanceof DictNode) || item.value.items.length > 0);
};