"""
db.py — Simple JSON file database
No MongoDB. No setup. Just a file on disk.
Data is saved in data.json automatically.
"""
import json
import os
import uuid
from datetime import datetime

DB_FILE = "data.json"

def _load():
    if not os.path.exists(DB_FILE):
        return {"users": {}, "expenses": {}, "debts": {}, "goals": {}}
    with open(DB_FILE, "r") as f:
        return json.load(f)

def _save(data):
    with open(DB_FILE, "w") as f:
        json.dump(data, f, indent=2, default=str)

def new_id():
    return str(uuid.uuid4())

def now():
    return datetime.utcnow().isoformat()

# ── Users ──────────────────────────────────────────────────────────────────────
def get_user_by_email(email):
    db = _load()
    for u in db["users"].values():
        if u["email"] == email:
            return u
    return None

def get_user_by_id(uid):
    return _load()["users"].get(uid)

def create_user(name, email, password_hash, income, currency="PKR"):
    db  = _load()
    uid = new_id()
    db["users"][uid] = {
        "id": uid, "name": name, "email": email,
        "password": password_hash, "income": income,
        "currency": currency, "created_at": now()
    }
    _save(db)
    return db["users"][uid]

def update_user_income(uid, income):
    db = _load()
    if uid in db["users"]:
        db["users"][uid]["income"] = income
        _save(db)

# ── Expenses ──────────────────────────────────────────────────────────────────
def add_expense(user_id, description, amount, type_, category, notes=None):
    db  = _load()
    eid = new_id()
    db["expenses"][eid] = {
        "id": eid, "user_id": user_id, "description": description,
        "amount": amount, "type": type_, "category": category,
        "notes": notes, "date": now()
    }
    _save(db)
    return db["expenses"][eid]

def get_expenses(user_id):
    db = _load()
    return [e for e in db["expenses"].values() if e["user_id"] == user_id]

def delete_expense(expense_id, user_id):
    db = _load()
    if expense_id in db["expenses"] and db["expenses"][expense_id]["user_id"] == user_id:
        del db["expenses"][expense_id]
        _save(db)
        return True
    return False

# ── Debts ─────────────────────────────────────────────────────────────────────
def add_debt(user_id, name, principal, interest_rate, monthly_payment, loan_type):
    db  = _load()
    did = new_id()
    db["debts"][did] = {
        "id": did, "user_id": user_id, "name": name,
        "principal": principal, "interest_rate": interest_rate,
        "monthly_payment": monthly_payment, "loan_type": loan_type,
        "created_at": now()
    }
    _save(db)
    return db["debts"][did]

def get_debts(user_id):
    db = _load()
    return [d for d in db["debts"].values() if d["user_id"] == user_id]

def delete_debt(debt_id, user_id):
    db = _load()
    if debt_id in db["debts"] and db["debts"][debt_id]["user_id"] == user_id:
        del db["debts"][debt_id]
        _save(db)
        return True
    return False

# ── Goals ─────────────────────────────────────────────────────────────────────
def add_goal(user_id, name, emoji, target_amount, monthly_contribution):
    db  = _load()
    gid = new_id()
    db["goals"][gid] = {
        "id": gid, "user_id": user_id, "name": name, "emoji": emoji,
        "target_amount": target_amount, "current_amount": 0,
        "monthly_contribution": monthly_contribution, "created_at": now()
    }
    _save(db)
    return db["goals"][gid]

def get_goals(user_id):
    db = _load()
    return [g for g in db["goals"].values() if g["user_id"] == user_id]

def contribute_goal(goal_id, user_id, amount):
    db = _load()
    if goal_id in db["goals"] and db["goals"][goal_id]["user_id"] == user_id:
        db["goals"][goal_id]["current_amount"] += amount
        _save(db)
        return db["goals"][goal_id]
    return None

def delete_goal(goal_id, user_id):
    db = _load()
    if goal_id in db["goals"] and db["goals"][goal_id]["user_id"] == user_id:
        del db["goals"][goal_id]
        _save(db)
        return True
    return False