"""Report generation: Excel / Word / PDF."""
import uuid
from pathlib import Path
from uuid import UUID

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.core.config import settings
from app.models.assessment import FraudAssessment, ReviewStatus
from app.models.transaction import TransactionRecord
from app.models.report import ExportReport, ReportType
from app.schemas.report import ReportCreate


async def generate_report(case_id: UUID, body: ReportCreate, db: AsyncSession) -> ExportReport:
    result = await db.execute(
        select(ExportReport)
        .where(ExportReport.case_id == case_id, ExportReport.report_type == body.report_type)
    )
    existing = list(result.scalars().all())
    version = len(existing) + 1

    report_dir = settings.upload_path / str(case_id) / "reports"
    report_dir.mkdir(parents=True, exist_ok=True)

    if body.report_type == ReportType.excel:
        file_path = await _gen_excel(case_id, report_dir, db)
    elif body.report_type == ReportType.word:
        file_path = await _gen_word(case_id, report_dir, db)
    else:
        file_path = await _gen_pdf_placeholder(case_id, report_dir)

    relative = str(file_path.relative_to(settings.upload_path))

    # snapshot confirmed assessments
    snap_result = await db.execute(
        select(FraudAssessment).where(
            FraudAssessment.case_id == case_id,
            FraudAssessment.review_status == ReviewStatus.confirmed,
        )
    )
    snapshot = [
        {"amount": float(a.assessed_amount), "reason": a.reason}
        for a in snap_result.scalars().all()
    ]

    report = ExportReport(
        case_id=case_id,
        report_type=body.report_type,
        file_path=relative,
        version=version,
        content_snapshot={"assessments": snapshot},
    )
    db.add(report)
    await db.flush()
    await db.refresh(report)
    return report


async def _gen_excel(case_id: UUID, report_dir: Path, db: AsyncSession) -> Path:
    from openpyxl import Workbook

    wb = Workbook()

    # Sheet 1: Summary
    ws = wb.active
    ws.title = "被骗金额汇总"
    ws.append(["交易时间", "金额(元)", "方向", "对方", "来源APP", "备注", "置信度", "认定理由"])

    assessments_result = await db.execute(
        select(FraudAssessment).where(
            FraudAssessment.case_id == case_id,
            FraudAssessment.review_status == ReviewStatus.confirmed,
        )
    )
    for a in assessments_result.scalars().all():
        tx = await db.get(TransactionRecord, a.transaction_id)
        if tx:
            ws.append([
                tx.trade_time.strftime("%Y-%m-%d %H:%M:%S"),
                float(a.assessed_amount),
                "支出" if tx.direction.value == "out" else "收入",
                tx.counterparty_name,
                tx.source_app.value,
                tx.remark,
                tx.confidence,
                a.reason[:100],
            ])

    # Sheet 2: All transactions
    ws2 = wb.create_sheet("交易明细")
    ws2.append(["交易时间", "金额", "方向", "对方", "来源", "订单号", "是否重复", "是否中转"])
    tx_result = await db.execute(
        select(TransactionRecord).where(TransactionRecord.case_id == case_id)
    )
    for tx in tx_result.scalars().all():
        ws2.append([
            tx.trade_time.strftime("%Y-%m-%d %H:%M:%S"),
            float(tx.amount),
            tx.direction.value,
            tx.counterparty_name,
            tx.source_app.value,
            tx.order_no,
            "是" if tx.is_duplicate else "否",
            "是" if tx.is_transit else "否",
        ])

    file_path = report_dir / f"report_{uuid.uuid4().hex[:8]}.xlsx"
    wb.save(file_path)
    return file_path


async def _gen_word(case_id: UUID, report_dir: Path, db: AsyncSession) -> Path:
    from docx import Document

    doc = Document()
    doc.add_heading("受害人被骗金额汇总报告", level=1)

    assessments_result = await db.execute(
        select(FraudAssessment).where(
            FraudAssessment.case_id == case_id,
            FraudAssessment.review_status == ReviewStatus.confirmed,
        )
    )
    confirmed = list(assessments_result.scalars().all())
    total = sum(float(a.assessed_amount) for a in confirmed)

    doc.add_paragraph(f"已确认被骗金额: ¥{total:,.2f}")
    doc.add_paragraph(f"已确认交易笔数: {len(confirmed)}")

    table = doc.add_table(rows=1, cols=4)
    table.style = "Table Grid"
    hdr = table.rows[0].cells
    hdr[0].text = "交易时间"
    hdr[1].text = "金额(元)"
    hdr[2].text = "对方"
    hdr[3].text = "认定理由"

    for a in confirmed:
        tx = await db.get(TransactionRecord, a.transaction_id)
        row = table.add_row().cells
        row[0].text = tx.trade_time.strftime("%Y-%m-%d %H:%M") if tx else ""
        row[1].text = f"{float(a.assessed_amount):,.2f}"
        row[2].text = tx.counterparty_name if tx else ""
        row[3].text = a.reason[:80]

    file_path = report_dir / f"report_{uuid.uuid4().hex[:8]}.docx"
    doc.save(file_path)
    return file_path


async def _gen_pdf_placeholder(case_id: UUID, report_dir: Path) -> Path:
    file_path = report_dir / f"report_{uuid.uuid4().hex[:8]}.pdf"
    file_path.write_text("PDF report placeholder – integrate weasyprint/reportlab for production.")
    return file_path