from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select
from ..database import get_db
from ..models import Student, Syllabus, TestPlan, TestPaper, TestAttempt, AnalysisReport, TokenUsage
from ..services import ai_service
from ..services.graph_service import generate_all_graphs
import uuid

router = APIRouter(prefix="/api/analysis", tags=["Analysis"])


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


async def _gather_attempts(student_id: str, syllabus_id: str, db: AsyncSession) -> list[dict]:
    plan_result = await db.execute(select(TestPlan).where(TestPlan.syllabus_id == syllabus_id))
    plan = plan_result.scalar_one_or_none()
    if not plan:
        return []

    papers_result = await db.execute(select(TestPaper).where(TestPaper.test_plan_id == plan.id))
    paper_ids = {p.id: p for p in papers_result.scalars().all()}

    attempts_result = await db.execute(
        select(TestAttempt).where(
            TestAttempt.student_id == student_id,
            TestAttempt.test_paper_id.in_(list(paper_ids.keys()))
        ).order_by(TestAttempt.attempted_at)
    )
    attempts = attempts_result.scalars().all()

    return [
        {
            "test_title": paper_ids[a.test_paper_id].title,
            "percentage": a.percentage,
            "score": a.score,
            "total_marks": a.total_marks,
            "is_targeted": paper_ids[a.test_paper_id].is_targeted,
            "evaluation": a.evaluation,
            "attempted_at": a.attempted_at.isoformat(),
        }
        for a in attempts
    ]


@router.post("/generate/{student_id}/{syllabus_id}")
async def generate_analysis(student_id: str, syllabus_id: str, db: AsyncSession = Depends(get_db)):
    student_result = await db.execute(select(Student).where(Student.id == student_id))
    student = student_result.scalar_one_or_none()
    if not student:
        raise HTTPException(404, "Student not found")

    syllabus_result = await db.execute(select(Syllabus).where(Syllabus.id == syllabus_id))
    syllabus = syllabus_result.scalar_one_or_none()
    if not syllabus:
        raise HTTPException(404, "Syllabus not found")

    attempts = await _gather_attempts(student_id, syllabus_id, db)
    if not attempts:
        raise HTTPException(400, "No test attempts found for this student/syllabus combination")

    existing_result = await db.execute(
        select(AnalysisReport).where(
            AnalysisReport.student_id == student_id,
            AnalysisReport.syllabus_id == syllabus_id
        ).order_by(AnalysisReport.version.desc())
    )
    existing = existing_result.scalars().first()
    prev_report = None
    if existing:
        prev_report = {
            "version": existing.version,
            "overall_score": existing.overall_score,
            "weaknesses": existing.weaknesses,
            "strengths": existing.strengths,
        }

    analysis, usage = await ai_service.analyze_performance(
        student_name=student.name,
        subject=syllabus.subject,
        grade=syllabus.grade,
        syllabus_topics=syllabus.topics,
        all_attempts=attempts,
        previous_report=prev_report,
    )

    version = (existing.version + 1) if existing else 1

    report = AnalysisReport(
        id=gen_id(),
        student_id=student_id,
        syllabus_id=syllabus_id,
        topic_performance=analysis["topic_performance"],
        overall_score=analysis["overall_score"],
        strengths=analysis["strengths"],
        weaknesses=analysis["weaknesses"],
        recommendations=analysis["recommendations"],
        narrative=analysis["narrative"],
        version=version,
        tests_analyzed=len(attempts),
    )
    db.add(report)
    db.add(TokenUsage(
        id=gen_id(),
        event_type="performance_analysis",
        student_id=student_id,
        student_name=student.name,
        syllabus_id=syllabus_id,
        subject=syllabus.subject,
        grade=syllabus.grade,
        input_tokens=usage["input_tokens"],
        output_tokens=usage["output_tokens"],
        total_tokens=usage["total_tokens"],
        model=usage["model"],
        extra_info={"tests_analyzed": len(attempts), "report_version": version},
    ))
    await db.commit()

    return {
        "report_id": report.id,
        "version": version,
        "overall_score": analysis["overall_score"],
        "topic_performance": analysis["topic_performance"],
        "strengths": analysis["strengths"],
        "weaknesses": analysis["weaknesses"],
        "recommendations": analysis["recommendations"],
        "narrative": analysis["narrative"],
        "tests_analyzed": len(attempts),
    }


@router.get("/{student_id}/{syllabus_id}")
async def get_analysis(student_id: str, syllabus_id: str, db: AsyncSession = Depends(get_db)):
    result = await db.execute(
        select(AnalysisReport).where(
            AnalysisReport.student_id == student_id,
            AnalysisReport.syllabus_id == syllabus_id
        ).order_by(AnalysisReport.version.desc())
    )
    report = result.scalars().first()
    if not report:
        raise HTTPException(404, "No analysis report found. Generate one first.")

    return {
        "report_id": report.id,
        "version": report.version,
        "overall_score": report.overall_score,
        "topic_performance": report.topic_performance,
        "strengths": report.strengths,
        "weaknesses": report.weaknesses,
        "recommendations": report.recommendations,
        "narrative": report.narrative,
        "tests_analyzed": report.tests_analyzed,
        "updated_at": report.updated_at.isoformat(),
    }


@router.get("/graphs/{student_id}/{syllabus_id}")
async def get_graphs(student_id: str, syllabus_id: str, db: AsyncSession = Depends(get_db)):
    report_result = await db.execute(
        select(AnalysisReport).where(
            AnalysisReport.student_id == student_id,
            AnalysisReport.syllabus_id == syllabus_id
        ).order_by(AnalysisReport.version.desc())
    )
    report = report_result.scalars().first()
    if not report:
        raise HTTPException(404, "Generate analysis report first")

    attempts = await _gather_attempts(student_id, syllabus_id, db)
    graphs = generate_all_graphs(report.topic_performance, attempts)

    return {
        "student_id": student_id,
        "syllabus_id": syllabus_id,
        "graphs": graphs,
    }


@router.post("/targeted-test/{student_id}/{syllabus_id}")
async def generate_targeted_test(student_id: str, syllabus_id: str, db: AsyncSession = Depends(get_db)):
    student_result = await db.execute(select(Student).where(Student.id == student_id))
    student = student_result.scalar_one_or_none()
    if not student:
        raise HTTPException(404, "Student not found")

    syllabus_result = await db.execute(select(Syllabus).where(Syllabus.id == syllabus_id))
    syllabus = syllabus_result.scalar_one_or_none()
    if not syllabus:
        raise HTTPException(404, "Syllabus not found")

    report_result = await db.execute(
        select(AnalysisReport).where(
            AnalysisReport.student_id == student_id,
            AnalysisReport.syllabus_id == syllabus_id
        ).order_by(AnalysisReport.version.desc())
    )
    report = report_result.scalars().first()
    if not report:
        raise HTTPException(400, "Generate analysis report first before creating targeted tests")

    weak_topics = []
    weak_subtopics = []
    for tp in report.topic_performance:
        if tp.get("overall_score") is not None and tp["overall_score"] < 60:
            weak_topics.append(tp["topic"])
        for st in tp.get("subtopic_scores", []):
            if st.get("score") is not None and st["score"] < 60:
                weak_subtopics.append(st["name"])

    if not weak_topics and not weak_subtopics:
        weak_topics = [tp["topic"] for tp in report.topic_performance[:2]]

    paper_data, usage = await ai_service.generate_targeted_test(
        subject=syllabus.subject,
        grade=syllabus.grade,
        student_name=student.name,
        weak_topics=weak_topics,
        weak_subtopics=weak_subtopics,
        topic_details=syllabus.topics,
    )

    plan_result = await db.execute(select(TestPlan).where(TestPlan.syllabus_id == syllabus_id))
    plan = plan_result.scalar_one_or_none()

    paper = TestPaper(
        id=gen_id(),
        test_plan_id=plan.id,
        sequence_number=0,
        title=paper_data["title"],
        questions=paper_data["questions"],
        total_marks=paper_data["total_marks"],
        duration_minutes=paper_data["duration_minutes"],
        topics_covered=paper_data["topics_covered"],
        is_targeted=True,
        target_student_id=student_id,
    )
    db.add(paper)
    db.add(TokenUsage(
        id=gen_id(),
        event_type="targeted_test_generation",
        student_id=student_id,
        student_name=student.name,
        syllabus_id=syllabus_id,
        subject=syllabus.subject,
        grade=syllabus.grade,
        input_tokens=usage["input_tokens"],
        output_tokens=usage["output_tokens"],
        total_tokens=usage["total_tokens"],
        model=usage["model"],
        extra_info={"weak_topics": weak_topics, "question_count": len(paper_data["questions"])},
    ))
    await db.commit()

    return {
        "test_paper_id": paper.id,
        "title": paper.title,
        "total_marks": paper.total_marks,
        "duration_minutes": paper.duration_minutes,
        "topics_covered": paper.topics_covered,
        "focused_weak_areas": weak_topics + weak_subtopics,
        "questions_count": len(paper.questions),
    }