package io.github.lonamiwebs.overgram.parser;

import io.github.lonamiwebs.overgram.utils.CharacterIterator;

import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class TLReader {

    public static final Map<String, List<TLObject>> readTlObjects(final File file) {
        final Map<String, List<TLObject>> result = new HashMap<>();
        for (final Map.Entry<String, List<String>> entry : readTl(file).entrySet()) {
            final List<TLObject> objects = new ArrayList<>();
            for (final String string : entry.getValue()) {
                objects.add(TLObject.fromString(string));
            }
            result.put(entry.getKey(), objects);
        }
        return result;
    }

    private static Map<String, List<String>> readTl(final File file) {
        final Map<String, List<String>> result = new HashMap<>();

        String section = "types";
        try (final CharacterIterator iter = new CharacterIterator(new FileReader(file))) {
            String tmp;
            final StringBuilder builder = new StringBuilder();
            for (char c : iter) {
                switch (c) {
                    // Assume '/' only occurs in "// comments...\n"
                    case '/':
                        do {
                            c = iter.next();
                        } while (iter.hasNext() && c != '\n');
                        break;

                    // Assume '-' only occurs in "---sections---\n"
                    case '-':
                        if (builder.length() != 0) {
                            tmp = builder.toString().trim();
                            if (!tmp.isEmpty()) {
                                result.computeIfAbsent(section, k -> new ArrayList<>()).add(tmp);
                            }
                            builder.setLength(0);
                        }

                        do {
                            c = iter.next();
                            if (c != '-') {
                                builder.append(c);
                            }
                        } while (iter.hasNext() && c != '\n');
                        section = builder.toString().trim();
                        builder.setLength(0);
                        break;

                    // Definitions are separated by ';'
                    case ';':
                        tmp = builder.toString().trim();
                        if (!tmp.isEmpty()) {
                            result.computeIfAbsent(section, k -> new ArrayList<>()).add(tmp);
                        }
                        builder.setLength(0);
                        break;

                    default:
                        builder.append(c);
                        break;
                }
            }
        } catch (IOException ignored) {
        }

        return result;
    }
}