"""Journald JSON (-o json) log parser."""
from __future__ import annotations

import json
from typing import Iterator

from app.ingest.base import (
    SourceState, apply_patterns, epoch_micros_to_iso,
    make_entry_id, now_iso, SYSLOG_PRIORITY,
)
from app.services.models import LogPattern, RetrievedEntry


def _extract_message(raw: dict) -> str:
    msg = raw.get("MESSAGE", "")
    # journald encodes binary messages as arrays of ints
    if isinstance(msg, list):
        try:
            return bytes(msg).decode("utf-8", errors="replace")
        except Exception:
            return repr(msg)
    return str(msg)


def parse(
    lines: Iterator[str],
    source_id: str,
    compiled_patterns: list[tuple[LogPattern, object]],
    ingest_time: str | None = None,
) -> Iterator[RetrievedEntry]:
    ingest_time = ingest_time or now_iso()
    state = SourceState()

    for raw_line in lines:
        raw_line = raw_line.strip()
        if not raw_line:
            continue
        try:
            entry = json.loads(raw_line)
        except json.JSONDecodeError:
            continue

        if "__REALTIME_TIMESTAMP" not in entry:
            continue

        text = _extract_message(entry)
        if not text:
            continue

        ts_raw = entry["__REALTIME_TIMESTAMP"]
        ts_iso = epoch_micros_to_iso(ts_raw)

        priority = entry.get("PRIORITY", "")
        severity = SYSLOG_PRIORITY.get(str(priority))

        hostname = entry.get("_HOSTNAME", "")
        unit = entry.get("_SYSTEMD_UNIT") or entry.get("SYSLOG_IDENTIFIER", "")
        src = f"{source_id}:{hostname}:{unit}" if hostname else source_id

        repeat, out_of_order = state.observe(text, ts_iso)
        matched = apply_patterns(text, compiled_patterns)

        yield RetrievedEntry(
            entry_id=make_entry_id(src, state.sequence, text),
            source_id=src,
            sequence=state.sequence,
            timestamp_raw=ts_raw,
            timestamp_iso=ts_iso,
            ingest_time=ingest_time,
            severity=severity,
            repeat_count=repeat,
            out_of_order=out_of_order,
            matched_patterns=matched,
            text=text,
        )