from collections import defaultdict
from datetime import datetime, timedelta, timezone

from sqlalchemy import and_, func, select
from sqlalchemy.ext.asyncio import AsyncSession

from backend.app.models.archive import PrintArchive
from backend.app.models.printer import Printer


class FailureAnalysisService:
    """Service for analyzing print failure patterns."""

    def __init__(self, db: AsyncSession):
        self.db = db

    async def analyze_failures(
        self,
        days: int = 30,
        printer_id: int | None = None,
        project_id: int | None = None,
    ) -> dict:
        """Analyze failure patterns across archives.

        Args:
            days: Number of days to analyze
            printer_id: Optional filter by printer
            project_id: Optional filter by project

        Returns:
            Dictionary with failure analysis results
        """
        cutoff_date = datetime.now(timezone.utc) - timedelta(days=days)

        # Build base query
        base_filter = [PrintArchive.created_at >= cutoff_date]
        if printer_id:
            base_filter.append(PrintArchive.printer_id == printer_id)
        if project_id:
            base_filter.append(PrintArchive.project_id == project_id)

        # Total counts
        total_result = await self.db.execute(select(func.count(PrintArchive.id)).where(and_(*base_filter)))
        total_prints = total_result.scalar() or 0

        failed_result = await self.db.execute(
            select(func.count(PrintArchive.id)).where(
                and_(*base_filter, PrintArchive.status.in_(["failed", "aborted"]))
            )
        )
        failed_prints = failed_result.scalar() or 0

        failure_rate = (failed_prints / total_prints * 100) if total_prints > 0 else 0

        # Failures by reason
        reason_result = await self.db.execute(
            select(
                PrintArchive.failure_reason,
                func.count(PrintArchive.id).label("count"),
            )
            .where(and_(*base_filter, PrintArchive.status.in_(["failed", "aborted"])))
            .group_by(PrintArchive.failure_reason)
            .order_by(func.count(PrintArchive.id).desc())
        )
        failures_by_reason = {(row[0] or "Unknown"): row[1] for row in reason_result.fetchall()}

        # Failures by filament type
        filament_result = await self.db.execute(
            select(
                PrintArchive.filament_type,
                func.count(PrintArchive.id).label("count"),
            )
            .where(and_(*base_filter, PrintArchive.status.in_(["failed", "aborted"])))
            .group_by(PrintArchive.filament_type)
            .order_by(func.count(PrintArchive.id).desc())
        )
        failures_by_filament = {(row[0] or "Unknown"): row[1] for row in filament_result.fetchall()}

        # Failures by printer
        printer_result = await self.db.execute(
            select(
                PrintArchive.printer_id,
                func.count(PrintArchive.id).label("count"),
            )
            .where(
                and_(*base_filter, PrintArchive.status.in_(["failed", "aborted"]), PrintArchive.printer_id.isnot(None))
            )
            .group_by(PrintArchive.printer_id)
            .order_by(func.count(PrintArchive.id).desc())
        )
        failures_by_printer_id = {row[0]: row[1] for row in printer_result.fetchall()}

        # Get printer names
        if failures_by_printer_id:
            printers_result = await self.db.execute(
                select(Printer.id, Printer.name).where(Printer.id.in_(failures_by_printer_id.keys()))
            )
            printer_names = {row[0]: row[1] for row in printers_result.fetchall()}
            failures_by_printer = {
                printer_names.get(pid, f"Printer {pid}"): count for pid, count in failures_by_printer_id.items()
            }
        else:
            failures_by_printer = {}

        # Failures by hour of day
        failed_archives_result = await self.db.execute(
            select(PrintArchive.started_at).where(
                and_(
                    *base_filter,
                    PrintArchive.status.in_(["failed", "aborted"]),
                    PrintArchive.started_at.isnot(None),
                )
            )
        )
        failures_by_hour = defaultdict(int)
        for (started_at,) in failed_archives_result.fetchall():
            if started_at:
                hour = started_at.hour
                failures_by_hour[hour] += 1
        # Convert to dict with all 24 hours
        failures_by_hour_complete = {h: failures_by_hour.get(h, 0) for h in range(24)}

        # Recent failures
        recent_result = await self.db.execute(
            select(PrintArchive)
            .where(and_(*base_filter, PrintArchive.status.in_(["failed", "aborted"])))
            .order_by(PrintArchive.created_at.desc())
            .limit(10)
        )
        recent_failures = [
            {
                "id": a.id,
                "print_name": a.print_name or a.filename,
                "failure_reason": a.failure_reason,
                "filament_type": a.filament_type,
                "printer_id": a.printer_id,
                "created_at": a.created_at.isoformat() if a.created_at else None,
            }
            for a in recent_result.scalars().all()
        ]

        # Failure rate trend (by week)
        trend_data = []
        for i in range(min(days // 7, 12)):  # Up to 12 weeks
            week_end = datetime.now(timezone.utc) - timedelta(weeks=i)
            week_start = week_end - timedelta(weeks=1)

            week_filter = base_filter.copy()
            week_filter[0] = and_(
                PrintArchive.created_at >= week_start,
                PrintArchive.created_at < week_end,
            )

            week_total = await self.db.execute(select(func.count(PrintArchive.id)).where(and_(*week_filter)))
            week_failed = await self.db.execute(
                select(func.count(PrintArchive.id)).where(
                    and_(*week_filter, PrintArchive.status.in_(["failed", "aborted"]))
                )
            )

            total = week_total.scalar() or 0
            failed = week_failed.scalar() or 0
            rate = (failed / total * 100) if total > 0 else 0

            trend_data.append(
                {
                    "week_start": week_start.date().isoformat(),
                    "total_prints": total,
                    "failed_prints": failed,
                    "failure_rate": round(rate, 1),
                }
            )

        trend_data.reverse()  # Oldest first

        return {
            "period_days": days,
            "total_prints": total_prints,
            "failed_prints": failed_prints,
            "failure_rate": round(failure_rate, 1),
            "failures_by_reason": failures_by_reason,
            "failures_by_filament": failures_by_filament,
            "failures_by_printer": failures_by_printer,
            "failures_by_hour": failures_by_hour_complete,
            "recent_failures": recent_failures,
            "trend": trend_data,
        }