from fastapi import FastAPI, HTTPException
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel
from typing import Optional
import json, os

DB_FILE = "db.json"
app = FastAPI(
    title="Vehicle Maintenance API",
    docs_url="/",        # Swagger UI served at root
    redoc_url="/redoc"   # optional: keep ReDoc at /redoc
)


# Allow frontend calls for testing
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],  # you can restrict this in production
    allow_methods=["*"],
    allow_headers=["*"],
)

# ---------------- Pydantic Models ----------------
class Vehicle(BaseModel):
    regNo: str
    category: str
    currentOdometer: int
    date: str
    id: Optional[int] = None

class Part(BaseModel):
    partName: str
    category: str
    durationDays: int
    intervalKM: int
    id: Optional[int] = None

class MaintenanceLog(BaseModel):
    regNo: str
    partName: str
    category: str
    date: str
    nextServiceDate: str
    nextServiceKM: int
    nextDay: int
    nextKM: int
    id: Optional[int] = None

# ---------------- Helpers ----------------
def load_db():
    if not os.path.exists(DB_FILE):
        return {"vehicles": [], "parts": [], "maintenance_logs": []}
    try:
        with open(DB_FILE, "r") as f:
            content = f.read().strip()
            if not content:
                return {"vehicles": [], "parts": [], "maintenance_logs": []}
            return json.loads(content)
    except (json.JSONDecodeError, IOError):
        # fallback: reset db if corrupted
        return {"vehicles": [], "parts": [], "maintenance_logs": []}


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

def generate_id(items):
    if not items:
        return 1
    ids = [item["id"] for item in items if item.get("id") is not None]
    return (max(ids, default=0) if ids else 0) + 1

# ---------------- Vehicles CRUD ----------------
@app.get("/vehicles")
def get_vehicles():
    return load_db()["vehicles"]

@app.post("/vehicles")
def create_vehicle(vehicle: Vehicle):
    data = load_db()
    vehicle.id = generate_id(data["vehicles"])
    data["vehicles"].append(vehicle.dict())
    save_db(data)
    return vehicle

@app.put("/vehicles/{vid}")
def update_vehicle(vid: int, vehicle: Vehicle):
    data = load_db()
    for v in data["vehicles"]:
        if v["id"] == vid:
            v.update(vehicle.dict())
            save_db(data)
            return v
    raise HTTPException(status_code=404, detail="Vehicle not found")

@app.delete("/vehicles/{vid}")
def delete_vehicle(vid: int):
    data = load_db()
    new_list = [v for v in data["vehicles"] if v["id"] != vid]
    if len(new_list) == len(data["vehicles"]):
        raise HTTPException(status_code=404, detail="Vehicle not found")
    data["vehicles"] = new_list
    save_db(data)
    return {"success": True}

# ---------------- Parts CRUD ----------------
@app.get("/parts")
def get_parts():
    return load_db()["parts"]

@app.post("/parts")
def create_part(part: Part):
    data = load_db()
    part.id = generate_id(data["parts"])
    data["parts"].append(part.dict())
    save_db(data)
    return part

@app.put("/parts/{pid}")
def update_part(pid: int, part: Part):
    data = load_db()
    for p in data["parts"]:
        if p["id"] == pid:
            p.update(part.dict())
            save_db(data)
            return p
    raise HTTPException(status_code=404, detail="Part not found")

@app.delete("/parts/{pid}")
def delete_part(pid: int):
    data = load_db()
    new_list = [p for p in data["parts"] if p["id"] != pid]
    if len(new_list) == len(data["parts"]):
        raise HTTPException(status_code=404, detail="Part not found")
    data["parts"] = new_list
    save_db(data)
    return {"success": True}

# ---------------- Maintenance CRUD ----------------
@app.get("/maintenance")
def get_maintenance():
    return load_db()["maintenance_logs"]

@app.post("/maintenance")
def create_maintenance(log: MaintenanceLog):
    data = load_db()
    log.id = generate_id(data["maintenance_logs"])
    data["maintenance_logs"].append(log.dict())
    save_db(data)
    return log

@app.put("/maintenance/{mid}")
def update_maintenance(mid: int, log: MaintenanceLog):
    data = load_db()
    for l in data["maintenance_logs"]:
        if l["id"] == mid:
            l.update(log.dict())
            save_db(data)
            return l
    raise HTTPException(status_code=404, detail="Maintenance log not found")

@app.delete("/maintenance/{mid}")
def delete_maintenance(mid: int):
    data = load_db()
    new_list = [l for l in data["maintenance_logs"] if l["id"] != mid]
    if len(new_list) == len(data["maintenance_logs"]):
        raise HTTPException(status_code=404, detail="Maintenance log not found")
    data["maintenance_logs"] = new_list
    save_db(data)
    return {"success": True}