src/api.py

import uvicorn
from fastapi import FastAPI, HTTPException, UploadFile, File, Form
from pydantic import BaseModel, Field
from transformers import pipeline
import torch
import os
import json
import httpx
import shutil
import whisper
import librosa
import numpy as np
from dotenv import load_dotenv
from typing import Optional, List
import uuid

try:
    from src.pronunciation import grade_pronunciation_advanced
except ImportError:
    from pronunciation import grade_pronunciation_advanced

load_dotenv()

SCORER_MODEL_ID_TASK1 = "diminch/ielts-task1-grader-ai-v2"
SCORER_MODEL_ID_TASK2 = "diminch/ielts-grader-ai-v2"

DEVICE = "cuda:0" if torch.cuda.is_available() else "cpu"
print(f"API running on: {DEVICE}")

OPENAI_API_KEY = os.getenv("OPENAI_API_KEY")
OPENAI_API_URL = "https://api.openai.com/v1/chat/completions"

if not OPENAI_API_KEY:
    print("WARNING: OPENAI_API_KEY not found in .env")

print("Loading Whisper...")
try:
    whisper_model = whisper.load_model("base", device=DEVICE)
    print("Whisper Loaded.")
except Exception as e:
    print(f"Error loading Whisper: {e}")
    whisper_model = None

pipelines = {}
def load_writing_model(task_name, model_id):
    try:
        print(f"Loading {task_name}: {model_id}...")
        pipelines[task_name] = pipeline(
            "text-classification", model=model_id, tokenizer=model_id,
            device=DEVICE, return_all_scores=True
        )
        print(f"Loaded {task_name}.")
    except Exception as e:
        print(f"Error loading {task_name}: {e}")
        pipelines[task_name] = None

load_writing_model("task1", SCORER_MODEL_ID_TASK1)
load_writing_model("task2", SCORER_MODEL_ID_TASK2)

class WritingRequest(BaseModel):
    task_type: int
    prompt: str
    essay: str
    image_url: Optional[str] = None

class WritingScores(BaseModel):
    taskResponse: float
    coherenceCohesion: float
    lexicalResource: float
    grammaticalRange: float

class ShortFeedbackWriting(BaseModel):
    taskResponse: str
    coherenceCohesion: str
    lexicalResource: str
    grammaticalRange: str

class WritingResponse(BaseModel):
    overallScore: float
    imageDescription: Optional[str] = None
    criteriaScores: WritingScores
    shortFeedback: ShortFeedbackWriting
    detailedFeedback: str

class SpeakingScores(BaseModel):
    fluencyCoherence: float
    lexicalResource: float
    grammaticalRange: float
    pronunciation: float

class PronunciationWord(BaseModel):
    word: str
    score: int
    phonemes_expected: str
    phonemes_actual: str
    is_correct: bool
    error_type: Optional[str] = None

class SpeakingResponse(BaseModel):
    overallScore: float
    transcript: str
    refinedTranscript: str
    betterVersion: str
    criteriaScores: SpeakingScores
    shortFeedback: dict
    detailedFeedback: str
    pronunciationBreakdown: List[PronunciationWord]

def round_to_half(score: float) -> float:
    return round(score * 2) / 2

async def analyze_chart_image(image_url: str, prompt_text: str) -> str:
    """Vision AI for Task 1"""
    if not image_url: return "No image provided."
    print("Analyzing chart image...")
    
    headers = { "Authorization": f"Bearer {OPENAI_API_KEY}", "Content-Type": "application/json" }
    vision_prompt = f"""
    Act as a data analyst. Describe this IELTS Writing Task 1 image in detail. 
    Focus strictly on the main trends, comparisons, and specific data points mentioned in the prompt: "{prompt_text}".
    Output a factual description paragraph representing the 'Ground Truth' of the image.
    """
    payload = {
        "model": "gpt-4o",
        "messages": [{"role": "user", "content": [
            {"type": "text", "text": vision_prompt},
            {"type": "image_url", "image_url": {"url": image_url}}
        ]}],
        "max_tokens": 500
    }
    async with httpx.AsyncClient(timeout=60.0) as client:
        try:
            resp = await client.post(OPENAI_API_URL, headers=headers, json=payload)
            return resp.json()['choices'][0]['message']['content']
        except Exception as e:
            print(f"Vision Error: {e}")
            return ""

async def generate_writing_feedback(prompt: str, essay: str, scores: WritingScores, task_type: int, img_desc: str = "") -> dict:
    print("Generating Writing feedback...")
    scores_dict = scores.model_dump()
    
    context_info = ""
    criterion_1_name = "Task Response"
    if task_type == 1:
        context_info = f"IMAGE GROUND TRUTH: {img_desc}\n(Check if the student accurately reported this data)"
        criterion_1_name = "Task Achievement"

    system_prompt = f"""
    You are a strict, expert IELTS Examiner.
    
    TASK INFO:
    - Type: Task {task_type}
    - Prompt: "{prompt}"
    {context_info}
    
    STUDENT ESSAY:
    "{essay}"
    
    SCORES GIVEN (0-9):
    {json.dumps(scores_dict)}
    
    YOUR GOAL:
    Provide a deeply analytical and educational feedback JSON.
    
    INSTRUCTIONS FOR 'detailedFeedback':
    The 'detailedFeedback' field MUST be a long Markdown string structured as follows:
    
    1. **General Overview**: A brief summary of why the essay got this band score.
    2. **Strengths & Weaknesses**: Bullet points highlighting what was done well and what was missing in each criteria (one by one, four criterias in total).
    3. **Specific Corrections (CRITICAL)**:
       - Identify 3-4 specific errors (grammar, vocab, or data accuracy).
       - For each error, show the "Original Text" -> "Correction" -> "Explanation".
       - Example: *Original: "The data shows an increase." -> Better: "The data illustrates a significant upward trend." (Explanation: Use more precise academic vocabulary).*
    4. **Actionable Advice**: Give 2-3 concrete steps the student should take to improve their score next time.
    
    Output JSON format:
    {{
        "shortFeedback": {{ 
            "{criterion_1_name}": "...", 
            "Coherence and Cohesion": "...", 
            "Lexical Resource": "...", 
            "Grammatical Range and Accuracy": "..." 
        }},
        "detailedFeedback": "MARKDOWN STRING..."
    }}
    """
    
    payload = {
        "model": "gpt-4o-mini",
        "messages": [{"role": "system", "content": system_prompt}],
        "response_format": {"type": "json_object"}
    }
    async with httpx.AsyncClient(timeout=60.0) as client:
        resp = await client.post(OPENAI_API_URL, headers={"Authorization": f"Bearer {OPENAI_API_KEY}"}, json=payload)
        return json.loads(resp.json()['choices'][0]['message']['content'])

app = FastAPI(title="IELTS Full-Stack AI API (V15.0)")

@app.post("/grade/writing", response_model=WritingResponse)
async def grade_writing(request: WritingRequest):
    model = pipelines.get(f"task{request.task_type}")
    if not model: raise HTTPException(500, "Model not ready.")
    
    image_desc = ""
    if request.task_type == 1:
        if not request.image_url: raise HTTPException(400, "Task 1 requires image_url.")
        image_desc = await analyze_chart_image(request.image_url, request.prompt)
        final_input = f"PROMPT: {request.prompt}\n\nIMAGE CONTEXT: {image_desc} [SEP] {request.essay}"
    else:
        final_input = f"{request.prompt} [SEP] {request.essay}"

    results = model(final_input, truncation=True, max_length=512)[0]
    raw = {item['label']: item['score'] for item in results}
    
    def r(x): return round(x * 2) / 2
    
    scores = WritingScores(
        taskResponse=r(raw.get('LABEL_0', 1.0)),
        coherenceCohesion=r(raw.get('LABEL_1', 1.0)),
        lexicalResource=r(raw.get('LABEL_2', 1.0)),
        grammaticalRange=r(raw.get('LABEL_3', 1.0))
    )
    overall = r((scores.taskResponse + scores.coherenceCohesion + 
                 scores.lexicalResource + scores.grammaticalRange) / 4)
                 
    # Feedback
    fb = await generate_writing_feedback(request.prompt, request.essay, scores, request.task_type, image_desc)
    sf = fb.get("shortFeedback", {})
    
    tr_fb = sf.get("Task Response") or sf.get("Task Achievement") or "No feedback"
    
    return WritingResponse(
        overallScore=overall,
        imageDescription=image_desc if request.task_type == 1 else None,
        criteriaScores=scores,
        shortFeedback=ShortFeedbackWriting(
            taskResponse=tr_fb,
            coherenceCohesion=sf.get("Coherence and Cohesion", ""),
            lexicalResource=sf.get("Lexical Resource", ""),
            grammaticalRange=sf.get("Grammatical Range and Accuracy", "")
        ),
        detailedFeedback=fb.get("detailedFeedback", "")
    )

async def grade_speaking_with_gpt(transcript: str, metrics: dict, ipa_data: dict, prompt_text: str) -> dict:
    """
    Generate Speaking feedback with Pronunciation Breakdown array.
    """
    print("Generating Speaking feedback...")
    
    system_prompt = f"""
    You are an expert IELTS Speaking Examiner and Phonetician.
    
    INPUT DATA:
    - Question: "{prompt_text}"
    - Transcript (Whisper): "{transcript}"
    - Raw Audio IPA (Actual): /{ipa_data.get('actual_ipa', '')}/
    - Expected IPA (Standard): /{ipa_data.get('expected_ipa', '')}/
    
    METRICS:
    - Speed: {metrics['wpm']:.1f} WPM
    - Pauses: {metrics['pause_ratio']*100:.1f}%
    
    YOUR TASK:
    1. Score the 4 criteria (0-9).
    2. **Pronunciation Breakdown**: Map words from Transcript to the IPA. Identify mispronounced words.
       - Compare Actual vs Expected IPA for each word.
       - Assign a score (1-10) for each word's pronunciation.
       - Flag errors (e.g., 'severe_substitution' if user said 'trip' but meant 'subject').
    
    OUTPUT JSON FORMAT (This is sample structure, replace with actual data):
    {{
        "scores": {{ "fluencyCoherence": 0.0, "lexicalResource": 0.0, "grammaticalRange": 0.0, "pronunciation": 0.0 }},
        "shortFeedback": {{ "Fluency": "...", "Vocabulary": "...", "Grammar": "...", "Pronunciation": "..." }},
        "detailedFeedback": "MARKDOWN string...",
        "refinedTranscript": "Corrected version...",
        "betterVersion": "Upgraded Band 8 version...",
        "pronunciationBreakdown": [
            {{
                "word": "subject",
                "score": 3,
                "phonemes_expected": "s ʌ b dʒ ɛ k t",
                "phonemes_actual": "t r ɪ p",
                "is_correct": false,
                "error_type": "severe_substitution"
            }},
            ... (more words)
        ]
    }}
    """
    
    payload = {
        "model": "gpt-4o-mini",
        "messages": [{"role": "system", "content": system_prompt}],
        "response_format": {"type": "json_object"}
    }
    
    async with httpx.AsyncClient(timeout=60.0) as client:
        resp = await client.post(OPENAI_API_URL, headers={"Authorization": f"Bearer {OPENAI_API_KEY}"}, json=payload)
        return json.loads(resp.json()['choices'][0]['message']['content'])

@app.post("/grade/speaking", response_model=SpeakingResponse)
async def grade_speaking(audio: UploadFile = File(...), prompt: str = Form(...)):
    temp_filename = f"temp_{uuid.uuid4()}.wav"
    try:
        with open(temp_filename, "wb") as buffer:
            shutil.copyfileobj(audio.file, buffer)
        
        # 1. Whisper & Acoustic Metrics
        if not whisper_model: raise HTTPException(500, "Whisper missing")
        res = whisper_model.transcribe(temp_filename)
        transcript = res["text"].strip()
        
        y, sr = librosa.load(temp_filename)
        duration = librosa.get_duration(y=y, sr=sr)
        word_count = len(transcript.split())
        wpm = (word_count / duration) * 60 if duration > 0 else 0
        non_silent = librosa.effects.split(y, top_db=20)
        silent_time = duration - sum([(e-s)/sr for s,e in non_silent])
        pause_ratio = silent_time / duration if duration > 0 else 0
        
        metrics = {"wpm": wpm, "pause_ratio": pause_ratio}

        # 2. IPA Analysis (Subprocess based)
        ipa_data = grade_pronunciation_advanced(temp_filename, transcript)
        
        # 3. GPT Analysis
        gpt_result = await grade_speaking_with_gpt(transcript, metrics, ipa_data, prompt)
        scores = gpt_result.get("scores", {})
        
        # 4. Response
        criteria = SpeakingScores(
            fluencyCoherence=round_to_half(scores.get("fluencyCoherence", 0)),
            lexicalResource=round_to_half(scores.get("lexicalResource", 0)),
            grammaticalRange=round_to_half(scores.get("grammaticalRange", 0)),
            pronunciation=round_to_half(scores.get("pronunciation", 0))
        )
        overall = round_to_half((criteria.fluencyCoherence + criteria.lexicalResource + 
                                 criteria.grammaticalRange + criteria.pronunciation) / 4)
        
        return SpeakingResponse(
            overallScore=overall,
            transcript=transcript,
            refinedTranscript=gpt_result.get("refinedTranscript", ""),
            betterVersion=gpt_result.get("betterVersion", ""),
            criteriaScores=criteria,
            shortFeedback=gpt_result.get("shortFeedback", {}),
            detailedFeedback=gpt_result.get("detailedFeedback", ""),
            pronunciationBreakdown=gpt_result.get("pronunciationBreakdown", [])
        )

    except Exception as e:
        print(f"Speaking Error: {e}")
        import traceback
        traceback.print_exc()
        raise HTTPException(500, str(e))
    finally:
        if os.path.exists(temp_filename): os.remove(temp_filename)

@app.get("/")
def read_root():
    return {"message": "IELTS API is running."}

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