from fastapi import FastAPI, HTTPException, BackgroundTasks
from fastapi.staticfiles import StaticFiles
from fastapi.responses import FileResponse, JSONResponse
from pydantic import BaseModel
import os
from dotenv import load_dotenv
import asyncio

# Load environment variables FIRST
load_dotenv()

# ⚙️ DEPLOYMENT CONFIGURATION
# FFmpeg Configuration - Tries to find FFmpeg automatically
import shutil

# Check if ffmpeg is already in system PATH
if shutil.which('ffmpeg') is None:
    # If not in PATH, try custom path (update this for your system)
    # Common Windows path: r"C:\ffmpeg\bin"
    # Linux/Mac: Usually already in PATH, no need to set
    custom_ffmpeg_path = os.environ.get('FFMPEG_PATH', r"M:\Ap\ffmpeg-7.1.1-essentials_build\ffmpeg-7.1.1-essentials_build\bin")
    
    if os.path.exists(custom_ffmpeg_path):
        os.environ["PATH"] += os.pathsep + custom_ffmpeg_path
        print(f"✅ FFmpeg found at: {custom_ffmpeg_path}")
    else:
        print("⚠️  FFmpeg not found in system PATH")
        print("   Options:")
        print("   1. Install FFmpeg and add to system PATH")
        print("   2. Set FFMPEG_PATH environment variable")
        print(f"   3. Update custom_ffmpeg_path in main.py (currently: {custom_ffmpeg_path})")
else:
    print("✅ FFmpeg found in system PATH")

from teacher import generate_outline
from compiler import generate_manim_code
from runner import render_scene
from narrator import generate_narration_audio

app = FastAPI()

# Get the directory of the current script (backend/)
BASE_DIR = os.path.dirname(os.path.abspath(__file__))
MEDIA_DIR = os.path.join(BASE_DIR, "media")
STATIC_DIR = os.path.join(BASE_DIR, "static")
# Root directory (parent of backend/)
ROOT_DIR = os.path.dirname(BASE_DIR)

# Ensure the media directory exists
os.makedirs(MEDIA_DIR, exist_ok=True)
app.mount("/media", StaticFiles(directory=MEDIA_DIR), name="media")

# Serve static frontend files
app.mount("/static", StaticFiles(directory=STATIC_DIR), name="static")

# Global Job Status
job_status = {
    "stage": "idle", # idle, planning, coding, executing, success, failed
    "message": "System Ready",
    "video_path": None,
    "error": None
}

class PromptRequest(BaseModel):
    prompt: str

async def process_video_generation(prompt: str):
    global job_status
    try:
        # 1. Planning
        job_status["stage"] = "planning"
        job_status["message"] = "Analyzing Prompt & Generating Outline..."
        outline = await generate_outline(prompt)
        

        # 2. Narrator: Generate per-step narration audio files
        steps = outline.get("steps", [])
        step_audio_paths = []
        from narrator import generate_narration_audio, concatenate_audio_files, get_audio_duration
        
        total_audio_duration = 0.0
        for idx, step in enumerate(steps):
            narration = step.get("narration", "")
            if narration:
                audio_filename = f"step_{idx+1}_narration.mp3"
                audio_path = generate_narration_audio(narration, filename=audio_filename)
                if audio_path:
                    step_audio_paths.append(audio_path)
                    duration = get_audio_duration(audio_path)
                    total_audio_duration += duration
                    print(f"✓ Step {idx+1} audio: {duration:.2f}s")
                else:
                    step_audio_paths.append(None)
            else:
                step_audio_paths.append(None)
        
        # Combine all step audios into one file
        combined_audio_path = None
        if step_audio_paths and any(step_audio_paths):
            combined_audio_path = concatenate_audio_files(step_audio_paths, output_filename="combined_narration.mp3")
            if combined_audio_path:
                print(f"✓ Combined audio duration: {total_audio_duration:.2f}s")

        # 3. Coding
        job_status["stage"] = "coding"
        job_status["message"] = "Generating Manim Script..."
        code = await generate_manim_code(outline, step_audio_paths=step_audio_paths)

        # 4. Executing
        job_status["stage"] = "executing"
        job_status["message"] = "Rendering Animation Frames..."
        video_path = await render_scene(code)

        # 5. Merge audio with video if available
        if combined_audio_path:
            from narrator import merge_audio_video
            job_status["message"] = "Merging Audio with Video..."
            video_path = merge_audio_video(video_path, combined_audio_path)
            print(f"✓ Final video with audio: {video_path}")

        # Success
        relative_path = os.path.relpath(video_path, start=MEDIA_DIR).replace("\\", "/")
        job_status["stage"] = "success"
        job_status["message"] = "Render Complete!"
        job_status["video_path"] = relative_path
        
    except Exception as e:
        error_msg = str(e)
        print(f"Error generating video: {error_msg}")
        job_status["stage"] = "failed"
        job_status["message"] = "Process Failed"
        job_status["error"] = error_msg
        
        # Log error
        with open("error.log", "w") as f:
            f.write(error_msg)
            import traceback
            traceback.print_exc(file=f)

@app.get("/")
async def read_index():
    return FileResponse(os.path.join(STATIC_DIR, 'index.html'))

@app.get("/favicon.ico")
async def get_favicon():
    favicon_path = os.path.join(ROOT_DIR, 'favicon.ico')
    if os.path.exists(favicon_path):
        return FileResponse(favicon_path)
    raise HTTPException(status_code=404, detail="Favicon not found")

@app.post("/generate")
async def generate_video(request: PromptRequest, background_tasks: BackgroundTasks):
    global job_status
    
    # Reset status
    job_status = {
        "stage": "planning",
        "message": "Initializing...",
        "video_path": None,
        "error": None
    }
    
    # Start background task
    background_tasks.add_task(process_video_generation, request.prompt)
    
    return {"status": "started"}

@app.get("/status")
async def get_status():
    return job_status

@app.get("/video/{path:path}")
async def get_video(path: str):
    video_path = os.path.join(MEDIA_DIR, path)
    if os.path.exists(video_path):
        return FileResponse(video_path)
    raise HTTPException(status_code=404, detail="Video not found")

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