package vn.kienutt.expense;

import android.content.*;
import android.database.*;
import android.database.sqlite.*;
import java.io.*;
import java.nio.charset.StandardCharsets;
import java.time.*;
import java.util.*;

public final class ExpenseDb extends SQLiteOpenHelper {
  private final Context context;

  public ExpenseDb(Context c) {
    super(c, "expenses.db", null, 1);
    context = c.getApplicationContext();
  }

  @Override
  public void onConfigure(SQLiteDatabase db) {
    db.setForeignKeyConstraintsEnabled(true);
  }

  @Override
  public void onCreate(SQLiteDatabase db) {
    try (InputStream in = context.getAssets().open("schema.sql")) {
      String sql = new String(read(in), StandardCharsets.UTF_8);
      for (String s : sql.split(";")) if (!s.trim().isEmpty()) db.execSQL(s);
    } catch (IOException e) {
      throw new IllegalStateException("Không đọc được schema", e);
    }
  }

  private static byte[] read(InputStream in) throws IOException {
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    byte[] b = new byte[4096];
    int n;
    while ((n = in.read(b)) != -1) out.write(b, 0, n);
    return out.toByteArray();
  }

  @Override
  public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
    throw new IllegalStateException("Cần viết migration giữ dữ liệu trước khi tăng phiên bản");
  }

  public static final class Entry {
    public final long id, amount;
    public final int category;
    public final String kind, day, note;

    Entry(Cursor c) {
      id = c.getLong(0);
      kind = c.getString(1);
      amount = c.getLong(2);
      category = c.getInt(3);
      day = c.getString(4);
      note = c.getString(5);
    }
  }

  public static final class Month {
    public final List<Entry> entries = new ArrayList<>();
    public String report;
  }

  public long save(long id, String kind, String amountText, int category, String day, String note) {
    if (!kind.equals("IN") && !kind.equals("OUT"))
      throw new IllegalArgumentException("Loại thu/chi sai");
    long amount = Long.parseLong(amountText);
    if (amount <= 0 || amount > 1000000000000L)
      throw new IllegalArgumentException("Số tiền phải từ 1 đến 1.000.000.000.000 đồng");
    if (!LocalDate.parse(day).toString().equals(day))
      throw new IllegalArgumentException("Ngày phải có dạng yyyy-MM-dd");
    if (note.length() > 500) throw new IllegalArgumentException("Ghi chú tối đa 500 ký tự");
    ContentValues v = new ContentValues();
    v.put("kind", kind);
    v.put("amount", amount);
    v.put("category_id", category);
    v.put("day", day);
    v.put("note", note);
    SQLiteDatabase db = getWritableDatabase();
    if (id == 0) return db.insertOrThrow("transactions", null, v);
    if (db.update("transactions", v, "id=?", new String[] {"" + id}) != 1)
      throw new IllegalArgumentException("Bản ghi không còn tồn tại");
    return id;
  }

  public void remove(long id) {
    if (getWritableDatabase().delete("transactions", "id=?", new String[] {"" + id}) != 1)
      throw new IllegalArgumentException("Không tìm thấy bản ghi");
  }

  public void budget(int category, String month, String amount) {
    String normalized = YearMonth.parse(month).toString();
    if (!normalized.equals(month)) throw new IllegalArgumentException("Tháng yyyy-MM");
    long limit = Long.parseLong(amount);
    if (limit <= 0 || limit > 1000000000000L)
      throw new IllegalArgumentException("Hạn mức ngoài phạm vi");
    ContentValues v = new ContentValues();
    v.put("category_id", category);
    v.put("month", month);
    v.put("limit_vnd", limit);
    getWritableDatabase().insertWithOnConflict("budgets", null, v, SQLiteDatabase.CONFLICT_REPLACE);
  }

  public Month month(String text) {
    YearMonth ym = YearMonth.parse(text);
    String from = ym.atDay(1).toString(), to = ym.plusMonths(1).atDay(1).toString();
    SQLiteDatabase db = getReadableDatabase();
    Month result = new Month();
    try (Cursor c = db.rawQuery(ExpenseSql.TOTALS, new String[] {from, to})) {
      c.moveToFirst();
      long income = c.getLong(0), outcome = c.getLong(1);
      result.report =
          "Thu: "
              + income
              + " đ · Chi: "
              + outcome
              + " đ\nChênh lệch thu − chi trong tháng: "
              + (income - outcome)
              + " đ";
    }
    try (Cursor c = db.rawQuery(ExpenseSql.BUDGETS, new String[] {from, to, text})) {
      while (c.moveToNext()) {
        long limit = c.getLong(1), used = c.getLong(2);
        result.report +=
            "\n"
                + c.getString(0)
                + ": "
                + used
                + " / "
                + limit
                + " đ"
                + (used > limit ? " · VƯỢT NGÂN SÁCH" : "");
      }
    }
    try (Cursor c =
        db.rawQuery(
            "SELECT id,kind,amount,category_id,day,note FROM transactions WHERE day>=? AND day<?"
                + " ORDER BY day DESC,id DESC LIMIT 100",
            new String[] {from, to})) {
      while (c.moveToNext()) result.entries.add(new Entry(c));
    }
    return result;
  }
}