from fastapi import FastAPI, HTTPException, Header, Depends, Request
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import RedirectResponse
from starlette.middleware.sessions import SessionMiddleware
from pydantic import BaseModel, Field, ConfigDict
from typing import List, Optional
from datetime import datetime
from sqlalchemy.orm import Session
from authlib.integrations.starlette_client import OAuth
import uuid
import hashlib
import os
from dotenv import load_dotenv

load_dotenv()

from database import init_db, get_db
import database as db_models

app = FastAPI(title="Tasko API", version="1.0.0")

# Initialize database
init_db()

# OAuth Configuration
oauth = OAuth()
oauth.register(
    name='google',
    client_id=os.getenv('GOOGLE_CLIENT_ID', ''),
    client_secret=os.getenv('GOOGLE_CLIENT_SECRET', ''),
    server_metadata_url='https://accounts.google.com/.well-known/openid-configuration',
    client_kwargs={
        'scope': 'openid email profile'
    }
)

allowed_origins = ["http://localhost:5173", "https://tasko.dvirlabs.com"]

# Environment-aware configuration
ENVIRONMENT = os.getenv('ENVIRONMENT', 'development')
is_production = ENVIRONMENT == 'production'
is_development = ENVIRONMENT == 'development'

# Configure Session Middleware (required for OAuth state/nonce storage)
# Generate a strong SECRET_KEY: python -c "import secrets; print(secrets.token_hex(32))"
SESSION_SECRET = os.getenv('SESSION_SECRET', 'dev-secret-change-in-production')

# Session cookie configuration - environment aware
session_config = {
    "secret_key": SESSION_SECRET,
    "session_cookie": "tasko_session",
    "max_age": 3600,  # 1 hour
    "path": "/",  # Available on all routes (required for OAuth callback)
    "same_site": "lax",  # Allows OAuth redirects while preventing CSRF
    "https_only": is_production,  # False for HTTP (dev), True for HTTPS (prod)
}

# Development-specific: Ensure cookies work on localhost
if is_development:
    session_config["domain"] = None  # Don't set domain for localhost

app.add_middleware(SessionMiddleware, **session_config)

# Log session configuration in development
if is_development:
    print(f"🔐 Session Configuration (Development Mode):")
    print(f"   - Cookie Name: {session_config['session_cookie']}")
    print(f"   - Path: {session_config['path']}")
    print(f"   - SameSite: {session_config['same_site']}")
    print(f"   - HTTPS Only: {session_config['https_only']}")
    print(f"   - Domain: {session_config.get('domain', 'None (localhost)')}")

# Configure CORS - MUST use specific origins (not "*") when allow_credentials=True
app.add_middleware(
    CORSMiddleware,
    allow_origins=allowed_origins,  # Specific origins required for credentials
    allow_credentials=True,  # Required for session cookies
    allow_methods=["*"],
    allow_headers=["*"],
    expose_headers=["*"],  # Allow frontend to read all response headers
)

# Log startup info
if is_development:
    print(f"🚀 Tasko API starting in DEVELOPMENT mode")
    print(f"   - CORS Origins: {allowed_origins}")
    print(f"   - Allow Credentials: True (session cookies enabled)")

# Pydantic Models for API
class UserResponse(BaseModel):
    model_config = ConfigDict(from_attributes=True)
    
    id: str
    username: str
    email: str
    created_at: datetime

class UserRegister(BaseModel):
    username: str
    email: str
    password: str

class UserLogin(BaseModel):
    model_config = ConfigDict(populate_by_name=True)
    
    username_or_email: str = Field(..., alias='usernameOrEmail')
    password: str

class AuthResponse(BaseModel):
    user: UserResponse
    token: str

class TaskListResponse(BaseModel):
    model_config = ConfigDict(from_attributes=True)
    
    id: str
    user_id: str
    name: str
    icon: str = "📝"
    color: str = "#667eea"
    created_at: datetime

class TaskListCreate(BaseModel):
    name: str
    icon: Optional[str] = "📝"
    color: Optional[str] = "#667eea"

class TaskListUpdate(BaseModel):
    name: Optional[str] = None
    icon: Optional[str] = None
    color: Optional[str] = None

class TaskResponse(BaseModel):
    model_config = ConfigDict(from_attributes=True)
    
    id: str
    list_id: str
    user_id: str
    title: str
    description: Optional[str] = None
    completed: bool = False
    priority: str = "medium"
    created_at: datetime
    updated_at: datetime

class TaskCreate(BaseModel):
    title: str
    list_id: str
    description: Optional[str] = None
    priority: str = "medium"

class TaskUpdate(BaseModel):
    title: Optional[str] = None
    description: Optional[str] = None
    completed: Optional[bool] = None
    priority: Optional[str] = None

def hash_password(password: str) -> str:
    return hashlib.sha256(password.encode()).hexdigest()

def verify_token(authorization: Optional[str], db: Session) -> str:
    if not authorization or not authorization.startswith("Bearer "):
        raise HTTPException(status_code=401, detail="Not authenticated")
    
    token_str = authorization.replace("Bearer ", "")
    token = db.query(db_models.Token).filter(db_models.Token.token == token_str).first()
    
    if not token:
        raise HTTPException(status_code=401, detail="Invalid token")
    
    return token.user_id

@app.get("/")
def read_root():
    return {"message": "Welcome to Tasko API"}

# Auth endpoints
@app.post("/register", response_model=AuthResponse)
def register(user_data: UserRegister, db: Session = Depends(get_db)):
    """Register a new user"""
    # Check if username or email exists (case-insensitive for username)
    existing_user = db.query(db_models.User).filter(
        (db_models.User.username.ilike(user_data.username)) | 
        (db_models.User.email == user_data.email)
    ).first()
    
    if existing_user:
        if existing_user.username == user_data.username:
            raise HTTPException(status_code=400, detail="Username already exists")
        else:
            raise HTTPException(status_code=400, detail="Email already exists")
    
    # Create user
    user_id = str(uuid.uuid4())
    new_user = db_models.User(
        id=user_id,
        username=user_data.username,
        email=user_data.email,
        password_hash=hash_password(user_data.password)
    )
    db.add(new_user)
    
    # Create token
    token_str = str(uuid.uuid4())
    new_token = db_models.Token(token=token_str, user_id=user_id)
    db.add(new_token)
    
    # Create default lists for new user
    default_lists = [
        {"name": "Personal", "icon": "🏠", "color": "#667eea"},
        {"name": "Work", "icon": "💼", "color": "#f093fb"},
        {"name": "Shopping", "icon": "🛒", "color": "#4facfe"},
    ]
    
    for list_data in default_lists:
        list_id = str(uuid.uuid4())
        new_list = db_models.TaskList(
            id=list_id,
            user_id=user_id,
            name=list_data["name"],
            icon=list_data["icon"],
            color=list_data["color"]
        )
        db.add(new_list)
    
    db.commit()
    db.refresh(new_user)
    
    return AuthResponse(
        user=UserResponse.model_validate(new_user),
        token=token_str
    )

@app.post("/login", response_model=AuthResponse)
def login(user_data: UserLogin, db: Session = Depends(get_db)):
    """Login a user with username or email"""
    password_hash = hash_password(user_data.password)
    
    # Try to find user by email or username (case-insensitive for username)
    user = db.query(db_models.User).filter(
        ((db_models.User.email == user_data.username_or_email) | 
         (db_models.User.username.ilike(user_data.username_or_email))),
        db_models.User.password_hash == password_hash
    ).first()
    
    if not user:
        raise HTTPException(status_code=401, detail="Invalid credentials")
    
    # Create new token
    token_str = str(uuid.uuid4())
    new_token = db_models.Token(token=token_str, user_id=user.id)
    db.add(new_token)
    db.commit()
    
    return AuthResponse(
        user=UserResponse.model_validate(user),
        token=token_str
    )

@app.post("/logout")
def logout(authorization: Optional[str] = Header(None), db: Session = Depends(get_db)):
    """Logout a user"""
    if authorization and authorization.startswith("Bearer "):
        token_str = authorization.replace("Bearer ", "")
        token = db.query(db_models.Token).filter(db_models.Token.token == token_str).first()
        if token:
            db.delete(token)
            db.commit()
    return {"message": "Logged out successfully"}

@app.get("/auth/google")
async def google_login(request: Request):
    """Initiate Google OAuth login - DIRECT BROWSER REDIRECT (not fetch)"""
    redirect_uri = os.getenv('GOOGLE_REDIRECT_URI', 'http://localhost:8000/auth/google/callback')
    
    # Debug logging for development
    if is_development:
        print(f"\n🔑 OAuth Login initiated (/auth/google):")
        print(f"   - Redirect URI: {redirect_uri}")
        print(f"   - Request URL: {request.url}")
        print(f"   - Request method: {request.method}")
        print(f"   - Request headers Cookie: {request.headers.get('cookie', 'NONE')}")
        print(f"   - Session available: {hasattr(request, 'session')}")
        if hasattr(request, 'session'):
            print(f"   - Session keys BEFORE: {list(request.session.keys())}")
    
    # This will set session state and redirect to Google
    response = await oauth.google.authorize_redirect(request, redirect_uri)
    
    if is_development:
        print(f"   - Session keys AFTER: {list(request.session.keys())}")
        print(f"   - Response status: {response.status_code}")
        print(f"   - Response Set-Cookie: {response.headers.get('set-cookie', 'NONE')}")
        print(f"   - Response Location: {response.headers.get('location', 'NONE')[:100]}...")
    
    return response

@app.get("/auth/google/callback")
async def google_callback(request: Request, db: Session = Depends(get_db)):
    """Handle Google OAuth callback"""
    try:
        # Debug logging for development
        if is_development:
            print(f"\n🔄 OAuth Callback received (/auth/google/callback):")
            print(f"   - Request URL: {request.url}")
            print(f"   - Request method: {request.method}")
            print(f"   - Request headers Cookie: {request.headers.get('cookie', 'NONE')}")
            print(f"   - Request query params: {dict(request.query_params)}")
            print(f"   - Cookies from request.cookies: {list(request.cookies.keys())}")
            print(f"   - Session available: {hasattr(request, 'session')}")
            if hasattr(request, 'session'):
                session_keys = list(request.session.keys())
                print(f"   - Session keys: {session_keys}")
                # Print state for debugging
                for key in session_keys:
                    if 'state' in key.lower():
                        value_str = str(request.session[key])
                        if len(value_str) > 100:
                            print(f"   - Session[{key}]: {value_str[:100]}...")
                        else:
                            print(f"   - Session[{key}]: {value_str}")
        
        # Get access token from Google
        token = await oauth.google.authorize_access_token(request)
        
        # Get user info from Google
        user_info = token.get('userinfo')
        if not user_info:
            raise HTTPException(status_code=400, detail="Failed to get user info from Google")
        
        email = user_info.get('email')
        google_id = user_info.get('sub')
        name = user_info.get('name', email.split('@')[0])
        
        # Check if user exists
        user = db.query(db_models.User).filter(db_models.User.email == email).first()
        
        if not user:
            # Create new user
            user_id = str(uuid.uuid4())
            # Use email username part as username, make it unique if needed
            username = email.split('@')[0]
            counter = 1
            original_username = username
            while db.query(db_models.User).filter(db_models.User.username.ilike(username)).first():
                username = f"{original_username}{counter}"
                counter += 1
            
            user = db_models.User(
                id=user_id,
                username=username,
                email=email,
                password_hash=hashlib.sha256(google_id.encode()).hexdigest()  # Use Google ID as password hash
            )
            db.add(user)
            
            # Create default lists for new user
            default_lists = [
                {"name": "Personal", "icon": "🏠", "color": "#667eea"},
                {"name": "Work", "icon": "💼", "color": "#f093fb"},
                {"name": "Shopping", "icon": "🛒", "color": "#4facfe"},
            ]
            
            for list_data in default_lists:
                list_id = str(uuid.uuid4())
                new_list = db_models.TaskList(
                    id=list_id,
                    user_id=user_id,
                    name=list_data["name"],
                    icon=list_data["icon"],
                    color=list_data["color"]
                )
                db.add(new_list)
            
            db.commit()
            db.refresh(user)
        
        # Create auth token
        token_str = str(uuid.uuid4())
        new_token = db_models.Token(token=token_str, user_id=user.id)
        db.add(new_token)
        db.commit()
        
        if is_development:
            print(f"✅ OAuth Login SUCCESS!")
            print(f"   - User: {user.email} (ID: {user.id})")
            print(f"   - Token generated: {token_str[:20]}...")
            print(f"   - Redirecting to frontend with token")
        
        # Redirect to frontend with token
        frontend_url = os.getenv('FRONTEND_URL', 'http://localhost:5173')
        return RedirectResponse(url=f"{frontend_url}?token={token_str}&user={user.id}")
        
    except Exception as e:
        if is_development:
            print(f"❌ OAuth Login FAILED: {str(e)}")
            import traceback
            traceback.print_exc()
        raise HTTPException(status_code=400, detail=f"Authentication failed: {str(e)}")

@app.get("/auth/google/url")
def get_google_auth_url():
    """Get Google OAuth URL for frontend"""
    redirect_uri = os.getenv('GOOGLE_REDIRECT_URI', 'http://localhost:8000/auth/google/callback')
    authorization_url = f"https://accounts.google.com/o/oauth2/v2/auth?client_id={os.getenv('GOOGLE_CLIENT_ID', '')}&redirect_uri={redirect_uri}&response_type=code&scope=openid%20email%20profile&access_type=offline&prompt=consent"
    return {"url": authorization_url}

@app.get("/api/user", response_model=UserResponse)
def get_current_user(authorization: Optional[str] = Header(None), db: Session = Depends(get_db)):
    """Get current user details"""
    user_id = verify_token(authorization, db)
    user = db.query(db_models.User).filter(db_models.User.id == user_id).first()
    
    if not user:
        raise HTTPException(status_code=404, detail="User not found")
    
    return UserResponse.model_validate(user)

# Task List endpoints
@app.get("/lists", response_model=List[TaskListResponse])
@app.get("/api/lists", response_model=List[TaskListResponse])
def get_task_lists(authorization: Optional[str] = Header(None), db: Session = Depends(get_db)):
    """Get all task lists for the authenticated user"""
    user_id = verify_token(authorization, db)
    task_lists = db.query(db_models.TaskList).filter(db_models.TaskList.user_id == user_id).all()
    return [TaskListResponse.model_validate(tl) for tl in task_lists]

@app.get("/lists/{list_id}", response_model=TaskListResponse)
@app.get("/api/lists/{list_id}", response_model=TaskListResponse)
def get_task_list(list_id: str, authorization: Optional[str] = Header(None), db: Session = Depends(get_db)):
    """Get a specific task list by ID"""
    user_id = verify_token(authorization, db)
    
    task_list = db.query(db_models.TaskList).filter(
        db_models.TaskList.id == list_id,
        db_models.TaskList.user_id == user_id
    ).first()
    
    if not task_list:
        raise HTTPException(status_code=404, detail="Task list not found")
    
    return TaskListResponse.model_validate(task_list)

@app.post("/lists", response_model=TaskListResponse, status_code=201)
@app.post("/api/lists", response_model=TaskListResponse, status_code=201)
def create_task_list(task_list: TaskListCreate, authorization: Optional[str] = Header(None), db: Session = Depends(get_db)):
    """Create a new task list"""
    user_id = verify_token(authorization, db)
    
    list_id = str(uuid.uuid4())
    new_list = db_models.TaskList(
        id=list_id,
        user_id=user_id,
        name=task_list.name,
        icon=task_list.icon or "📝",
        color=task_list.color or "#667eea"
    )
    
    db.add(new_list)
    db.commit()
    db.refresh(new_list)
    
    return TaskListResponse.model_validate(new_list)

@app.put("/lists/{list_id}", response_model=TaskListResponse)
@app.put("/api/lists/{list_id}", response_model=TaskListResponse)
def update_task_list(list_id: str, list_update: TaskListUpdate, authorization: Optional[str] = Header(None), db: Session = Depends(get_db)):
    """Update an existing task list"""
    user_id = verify_token(authorization, db)
    
    task_list = db.query(db_models.TaskList).filter(
        db_models.TaskList.id == list_id,
        db_models.TaskList.user_id == user_id
    ).first()
    
    if not task_list:
        raise HTTPException(status_code=404, detail="Task list not found")
    
    update_data = list_update.model_dump(exclude_unset=True)
    for field, value in update_data.items():
        setattr(task_list, field, value)
    
    db.commit()
    db.refresh(task_list)
    
    return TaskListResponse.model_validate(task_list)

@app.delete("/lists/{list_id}", status_code=204)
@app.delete("/api/lists/{list_id}", status_code=204)
def delete_task_list(list_id: str, authorization: Optional[str] = Header(None), db: Session = Depends(get_db)):
    """Delete a task list and all its tasks"""
    user_id = verify_token(authorization, db)
    
    task_list = db.query(db_models.TaskList).filter(
        db_models.TaskList.id == list_id,
        db_models.TaskList.user_id == user_id
    ).first()
    
    if not task_list:
        raise HTTPException(status_code=404, detail="Task list not found")
    
    # Tasks will be deleted automatically due to cascade relationship
    db.delete(task_list)
    db.commit()
    
    return None

# Task endpoints
@app.get("/tasks", response_model=List[TaskResponse])
@app.get("/api/tasks", response_model=List[TaskResponse])
def get_tasks(list_id: Optional[str] = None, authorization: Optional[str] = Header(None), db: Session = Depends(get_db)):
    """Get all tasks for authenticated user, optionally filtered by list_id"""
    user_id = verify_token(authorization, db)
    
    query = db.query(db_models.Task).filter(db_models.Task.user_id == user_id)
    
    if list_id:
        # Verify list belongs to user
        task_list = db.query(db_models.TaskList).filter(
            db_models.TaskList.id == list_id,
            db_models.TaskList.user_id == user_id
        ).first()
        
        if not task_list:
            raise HTTPException(status_code=403, detail="Access denied")
        
        query = query.filter(db_models.Task.list_id == list_id)
    
    tasks = query.all()
    return [TaskResponse.model_validate(t) for t in tasks]

@app.get("/tasks/{task_id}", response_model=TaskResponse)
@app.get("/api/tasks/{task_id}", response_model=TaskResponse)
def get_task(task_id: str, authorization: Optional[str] = Header(None), db: Session = Depends(get_db)):
    """Get a specific task by ID"""
    user_id = verify_token(authorization, db)
    
    task = db.query(db_models.Task).filter(
        db_models.Task.id == task_id,
        db_models.Task.user_id == user_id
    ).first()
    
    if not task:
        raise HTTPException(status_code=404, detail="Task not found")
    
    return TaskResponse.model_validate(task)

@app.post("/tasks", response_model=TaskResponse, status_code=201)
@app.post("/api/tasks", response_model=TaskResponse, status_code=201)
def create_task(task: TaskCreate, authorization: Optional[str] = Header(None), db: Session = Depends(get_db)):
    """Create a new task"""
    user_id = verify_token(authorization, db)
    
    # Verify list exists and belongs to user
    task_list = db.query(db_models.TaskList).filter(
        db_models.TaskList.id == task.list_id,
        db_models.TaskList.user_id == user_id
    ).first()
    
    if not task_list:
        raise HTTPException(status_code=404, detail="Task list not found")
    
    task_id = str(uuid.uuid4())
    new_task = db_models.Task(
        id=task_id,
        list_id=task.list_id,
        user_id=user_id,
        title=task.title,
        description=task.description,
        completed=False,
        priority=task.priority
    )
    
    db.add(new_task)
    db.commit()
    db.refresh(new_task)
    
    return TaskResponse.model_validate(new_task)

@app.put("/tasks/{task_id}", response_model=TaskResponse)
@app.put("/api/tasks/{task_id}", response_model=TaskResponse)
def update_task(task_id: str, task_update: TaskUpdate, authorization: Optional[str] = Header(None), db: Session = Depends(get_db)):
    """Update an existing task"""
    user_id = verify_token(authorization, db)
    
    task = db.query(db_models.Task).filter(
        db_models.Task.id == task_id,
        db_models.Task.user_id == user_id
    ).first()
    
    if not task:
        raise HTTPException(status_code=404, detail="Task not found")
    
    update_data = task_update.model_dump(exclude_unset=True)
    for field, value in update_data.items():
        setattr(task, field, value)
    
    task.updated_at = datetime.now()
    
    db.commit()
    db.refresh(task)
    
    return TaskResponse.model_validate(task)

@app.delete("/tasks/{task_id}", status_code=204)
@app.delete("/api/tasks/{task_id}", status_code=204)
def delete_task(task_id: str, authorization: Optional[str] = Header(None), db: Session = Depends(get_db)):
    """Delete a task"""
    user_id = verify_token(authorization, db)
    
    task = db.query(db_models.Task).filter(
        db_models.Task.id == task_id,
        db_models.Task.user_id == user_id
    ).first()
    
    if not task:
        raise HTTPException(status_code=404, detail="Task not found")
    
    db.delete(task)
    db.commit()
    
    return None

if __name__ == "__main__":
    import uvicorn
    uvicorn.run("main:app", host="0.0.0.0", port=8000, reload=True)