"""Event-line emission and CSV writers.

The ``emit_event`` output line is a contract with ``saqr.robot.bridge`` — its
regex parses this exact format. Don't change the field order without updating
the bridge.
"""
from __future__ import annotations

import csv
from datetime import datetime
from pathlib import Path
from typing import Dict, List

from saqr.core.compliance import split_wearing_missing
from saqr.core.detection import CLASS_ORDER


def now_iso() -> str:
    return datetime.now().isoformat(timespec="seconds")


class EventLogger:
    FIELDS = ["timestamp", "track_id", "event_type", "status",
              "wearing", "missing", "unknown", "photo", "path"]

    def __init__(self, path: Path):
        self.path = path
        self.path.parent.mkdir(parents=True, exist_ok=True)
        if not self.path.exists():
            with open(self.path, "w", newline="", encoding="utf-8") as f:
                csv.DictWriter(f, fieldnames=self.FIELDS).writeheader()

    def append(self, row: Dict[str, str]) -> None:
        with open(self.path, "a", newline="", encoding="utf-8") as f:
            csv.DictWriter(f, fieldnames=self.FIELDS).writerow(row)


def write_result_csv(tracks: List, output: Path) -> None:
    output.parent.mkdir(parents=True, exist_ok=True)
    fields = ["photo", "track_id", "status", "last_seen",
              "wearing", "missing", "unknown", *CLASS_ORDER, "path"]
    rows = []
    for track in sorted(tracks, key=lambda t: t.track_id):
        wearing, missing, unknown = split_wearing_missing(track.items)
        row = {
            "photo":     track.photo_path.name if track.photo_path else "",
            "track_id":  track.track_id,
            "status":    track.status,
            "last_seen": track.last_seen_iso,
            "wearing":   ", ".join(wearing),
            "missing":   ", ".join(missing),
            "unknown":   ", ".join(unknown),
            "path":      str(track.photo_path) if track.photo_path else "",
        }
        for cls in CLASS_ORDER:
            row[cls] = 1 if track.items.get(cls, 0.0) > 0 else 0
        rows.append(row)

    with open(output, "w", newline="", encoding="utf-8") as f:
        w = csv.DictWriter(f, fieldnames=fields)
        w.writeheader()
        w.writerows(rows)


def emit_event(track, event_logger: EventLogger, event_type: str = "STATUS_CHANGE",
               force: bool = False) -> None:
    if track.photo_path is None:
        return
    if not force and track.announced_status == track.status:
        return

    wearing, missing, unknown = split_wearing_missing(track.items)
    msg = (
        f"ID {track.track_id:04d} | {event_type} | {track.status} | "
        f"wearing: {', '.join(wearing) or 'none'} | "
        f"missing: {', '.join(missing) or 'none'} | "
        f"unknown: {', '.join(unknown) or 'none'}"
    )
    print(msg, flush=True)

    event_logger.append({
        "timestamp":  now_iso(),
        "track_id":   str(track.track_id),
        "event_type": event_type,
        "status":     track.status,
        "wearing":    ", ".join(wearing),
        "missing":    ", ".join(missing),
        "unknown":    ", ".join(unknown),
        "photo":      track.photo_path.name if track.photo_path else "",
        "path":       str(track.photo_path) if track.photo_path else "",
    })
    track.announced_status = track.status
    track.event_count += 1