"""Shared helpers for the burnin package.

Lives below stages.py / task.py / __init__.py — these all import from
here. _common itself imports nothing from sibling burnin modules so we
stay free of circular-import landmines.

Owns:
  * Stage configuration constants (STAGE_ORDER, _STAGE_BASE_WEIGHTS,
    POLL_INTERVAL).
  * The connection-helper context manager `_db()` and the `_now()` ISO
    timestamp helper used everywhere.
  * Per-stage DB mutators called by stage implementations and by the
    job orchestrator (`_start_stage`, `_finish_stage`, `_cancel_stage`,
    `_set_stage_error`, `_update_stage_percent`,
    `_update_stage_bad_blocks`, `_append_stage_log`).
  * Drive-row mutators for SMART caches
    (`_store_smart_attrs`, `_store_smart_raw_output`).
  * The job-state read (`_is_cancelled`) + progress aggregator
    (`_recalculate_progress`).
  * SSE notifier (`_push_update`).
"""

from __future__ import annotations

import json
import logging
from contextlib import asynccontextmanager
from datetime import datetime, timezone

import aiosqlite

from app.config import settings

log = logging.getLogger(__name__)


# ---------------------------------------------------------------------------
# Stage configuration
# ---------------------------------------------------------------------------

STAGE_ORDER: dict[str, list[str]] = {
    # Legacy
    "quick":         ["precheck", "short_smart", "io_validate", "final_check"],
    # Single-stage selectable profiles
    "surface":       ["precheck", "surface_validate", "final_check"],
    "short":         ["precheck", "short_smart", "final_check"],
    "long":          ["precheck", "long_smart", "final_check"],
    # Two-stage combos
    "surface_short": ["precheck", "surface_validate", "short_smart", "final_check"],
    "surface_long":  ["precheck", "surface_validate", "long_smart", "final_check"],
    "short_long":    ["precheck", "short_smart", "long_smart", "final_check"],
    # All three
    "full":          ["precheck", "surface_validate", "short_smart", "long_smart", "final_check"],
}

# Per-stage base weights used to compute overall job % progress dynamically
_STAGE_BASE_WEIGHTS: dict[str, int] = {
    "precheck":         5,
    "surface_validate": 65,
    "short_smart":      12,
    "long_smart":       13,
    "io_validate":      10,
    "final_check":       5,
}

POLL_INTERVAL = 5.0  # seconds between progress checks during active stages


# ---------------------------------------------------------------------------
# Connection helpers
# ---------------------------------------------------------------------------

def _now() -> str:
    return datetime.now(timezone.utc).isoformat()


@asynccontextmanager
async def _db():
    """Open a WAL-mode connection with busy_timeout so writers wait for the lock
    instead of immediately raising 'database is locked' under contention."""
    async with aiosqlite.connect(settings.db_path) as db:
        await db.execute("PRAGMA busy_timeout=10000")
        yield db


# ---------------------------------------------------------------------------
# Job / stage DB mutators
# ---------------------------------------------------------------------------

async def _is_cancelled(job_id: int) -> bool:
    async with _db() as db:
        cur = await db.execute("SELECT state FROM burnin_jobs WHERE id=?", (job_id,))
        row = await cur.fetchone()
        return bool(row and row[0] == "cancelled")


async def _start_stage(job_id: int, stage_name: str) -> None:
    async with _db() as db:
        await db.execute("PRAGMA journal_mode=WAL")
        await db.execute(
            "UPDATE burnin_stages SET state='running', started_at=? WHERE burnin_job_id=? AND stage_name=?",
            (_now(), job_id, stage_name),
        )
        await db.execute(
            "UPDATE burnin_jobs SET stage_name=? WHERE id=?",
            (stage_name, job_id),
        )
        await db.commit()


async def _finish_stage(job_id: int, stage_name: str, success: bool, error_text: str | None = None) -> None:
    now = _now()
    state = "passed" if success else "failed"
    async with _db() as db:
        await db.execute("PRAGMA journal_mode=WAL")
        cur = await db.execute(
            "SELECT started_at FROM burnin_stages WHERE burnin_job_id=? AND stage_name=?",
            (job_id, stage_name),
        )
        row = await cur.fetchone()
        duration = None
        if row and row[0]:
            try:
                start = datetime.fromisoformat(row[0])
                if start.tzinfo is None:
                    start = start.replace(tzinfo=timezone.utc)
                duration = (datetime.now(timezone.utc) - start).total_seconds()
            except Exception:
                pass

        # Only overwrite error_text if one is passed; otherwise preserve what the stage already wrote
        if error_text is not None:
            await db.execute(
                """UPDATE burnin_stages
                   SET state=?, percent=?, finished_at=?, duration_seconds=?, error_text=?
                   WHERE burnin_job_id=? AND stage_name=?""",
                (state, 100 if success else None, now, duration, error_text, job_id, stage_name),
            )
        else:
            await db.execute(
                """UPDATE burnin_stages
                   SET state=?, percent=?, finished_at=?, duration_seconds=?
                   WHERE burnin_job_id=? AND stage_name=?""",
                (state, 100 if success else None, now, duration, job_id, stage_name),
            )
        await db.commit()


async def _update_stage_percent(job_id: int, stage_name: str, pct: int) -> None:
    async with _db() as db:
        await db.execute("PRAGMA journal_mode=WAL")
        await db.execute(
            "UPDATE burnin_stages SET percent=? WHERE burnin_job_id=? AND stage_name=?",
            (pct, job_id, stage_name),
        )
        await db.commit()


async def _cancel_stage(job_id: int, stage_name: str) -> None:
    now = _now()
    async with _db() as db:
        await db.execute("PRAGMA journal_mode=WAL")
        await db.execute(
            "UPDATE burnin_stages SET state='cancelled', finished_at=? WHERE burnin_job_id=? AND stage_name=?",
            (now, job_id, stage_name),
        )
        await db.commit()


async def _append_stage_log(job_id: int, stage_name: str, text: str) -> None:
    """Append text to the log_text column of a burnin_stages row."""
    async with _db() as db:
        await db.execute("PRAGMA journal_mode=WAL")
        await db.execute(
            """UPDATE burnin_stages
               SET log_text = COALESCE(log_text, '') || ?
               WHERE burnin_job_id=? AND stage_name=?""",
            (text, job_id, stage_name),
        )
        await db.commit()


async def _update_stage_bad_blocks(job_id: int, stage_name: str, count: int) -> None:
    async with _db() as db:
        await db.execute("PRAGMA journal_mode=WAL")
        await db.execute(
            "UPDATE burnin_stages SET bad_blocks=? WHERE burnin_job_id=? AND stage_name=?",
            (count, job_id, stage_name),
        )
        await db.commit()


async def _store_smart_attrs(drive_id: int, attrs: dict) -> None:
    """Persist latest SMART attribute dict to drives.smart_attrs (JSON)."""
    # Convert int keys to str for JSON serialisation
    serialisable = {str(k): v for k, v in attrs.get("attributes", {}).items()}
    blob = json.dumps({
        "health":   attrs.get("health", "UNKNOWN"),
        "attrs":    serialisable,
        "warnings": attrs.get("warnings", []),
        "failures": attrs.get("failures", []),
    })
    async with _db() as db:
        await db.execute("PRAGMA journal_mode=WAL")
        await db.execute("UPDATE drives SET smart_attrs=? WHERE id=?", (blob, drive_id))
        await db.commit()


async def _store_smart_raw_output(drive_id: int, test_type: str, raw: str) -> None:
    """Store raw smartctl output in smart_tests.raw_output."""
    async with _db() as db:
        await db.execute("PRAGMA journal_mode=WAL")
        await db.execute(
            "UPDATE smart_tests SET raw_output=? WHERE drive_id=? AND test_type=?",
            (raw, drive_id, test_type.lower()),
        )
        await db.commit()


async def _set_stage_error(job_id: int, stage_name: str, error_text: str) -> None:
    async with _db() as db:
        await db.execute("PRAGMA journal_mode=WAL")
        await db.execute(
            "UPDATE burnin_stages SET error_text=? WHERE burnin_job_id=? AND stage_name=?",
            (error_text, job_id, stage_name),
        )
        await db.commit()


async def _recalculate_progress(job_id: int, profile: str | None = None) -> None:
    """Recompute overall job % from actual stage rows. profile param is unused (kept for compat)."""
    async with _db() as db:
        db.row_factory = aiosqlite.Row
        await db.execute("PRAGMA journal_mode=WAL")

        cur = await db.execute(
            "SELECT stage_name, state, percent FROM burnin_stages WHERE burnin_job_id=? ORDER BY id",
            (job_id,),
        )
        stages = await cur.fetchall()
        if not stages:
            return

        total_weight = sum(_STAGE_BASE_WEIGHTS.get(s["stage_name"], 5) for s in stages)
        if total_weight == 0:
            return

        completed = 0.0
        current = None
        for s in stages:
            w  = _STAGE_BASE_WEIGHTS.get(s["stage_name"], 5)
            st = s["state"]
            if st == "passed":
                completed += w
            elif st == "running":
                completed += w * (s["percent"] or 0) / 100
                current = s["stage_name"]

        pct = int(completed / total_weight * 100)
        await db.execute(
            "UPDATE burnin_jobs SET percent=?, stage_name=? WHERE id=?",
            (pct, current, job_id),
        )
        await db.commit()


# ---------------------------------------------------------------------------
# SSE notifier
# ---------------------------------------------------------------------------

def _push_update(alert: dict | None = None) -> None:
    """Notify SSE subscribers that data has changed, with optional browser notification payload."""
    try:
        from app import poller
        poller._notify_subscribers(alert=alert)
    except Exception:
        pass