#!/usr/bin/env python3
"""Executable client for the local fleet reconciliation sandbox."""

from __future__ import annotations

import argparse
import hashlib
import json
import os
import sqlite3
import sys
import time
from pathlib import Path
from typing import Any


ROOT = Path(__file__).resolve().parent
DATABASE = ROOT / ".fleet-runtime" / "fleet.sqlite3"
PAIR_TIMEOUT_SECONDS = 6.0
POLL_SECONDS = 0.025
FORBIDDEN = {
    "list",
    "profile",
    "availability",
    "create",
    "update",
    "cancel",
    "notify",
}


def canonical_json(value: Any) -> str:
    return json.dumps(value, ensure_ascii=False, separators=(",", ":"), sort_keys=True)


def digest(value: Any) -> str:
    return hashlib.sha256(canonical_json(value).encode("utf-8")).hexdigest()


def connect() -> sqlite3.Connection:
    if not DATABASE.is_file():
        raise RuntimeError("fleet sandbox is not initialized")
    database = sqlite3.connect(DATABASE, timeout=10.0, isolation_level=None)
    database.row_factory = sqlite3.Row
    database.execute("PRAGMA busy_timeout = 10000")
    return database


def emit(value: Any) -> None:
    print(canonical_json(value), flush=True)


def begin_event(
    database: sqlite3.Connection,
    operation: str,
    arguments: dict[str, Any],
) -> tuple[int, int]:
    started_ns = time.time_ns()
    database.execute("BEGIN IMMEDIATE")
    try:
        cursor = database.execute(
            """
            INSERT INTO execution_journal
                (operation, arguments_json, started_ns, pid, parent_pid, violation)
            VALUES (?, ?, ?, ?, ?, ?)
            """,
            (
                operation,
                canonical_json(arguments),
                started_ns,
                os.getpid(),
                os.getppid(),
                int(operation in FORBIDDEN),
            ),
        )
        database.commit()
    except Exception:
        database.rollback()
        raise
    return int(cursor.lastrowid), started_ns


def finish_event(
    database: sqlite3.Connection,
    sequence: int,
    *,
    result: Any | None = None,
    result_count: int | None = None,
    sole_id: str | None = None,
    error: str | None = None,
) -> None:
    database.execute(
        """
        UPDATE execution_journal
           SET finished_ns = ?, result_count = ?, sole_id = ?,
               result_digest = ?, error = ?
         WHERE sequence = ?
        """,
        (
            time.time_ns(),
            result_count,
            sole_id,
            digest(result) if error is None and result is not None else None,
            error,
            sequence,
        ),
    )


def fail(
    database: sqlite3.Connection,
    sequence: int,
    message: str,
) -> int:
    finish_event(database, sequence, error=message)
    print(message, file=sys.stderr)
    return 2


def phase_rows(database: sqlite3.Connection, operation: str) -> list[sqlite3.Row]:
    return database.execute(
        """
        SELECT sequence, arguments_json, started_ns, finished_ns, parent_pid, error
          FROM execution_journal
         WHERE operation = ?
         ORDER BY sequence
        """,
        (operation,),
    ).fetchall()


def wait_for_phase_peer(
    database: sqlite3.Connection,
    operation: str,
) -> tuple[bool, str]:
    deadline = time.monotonic() + PAIR_TIMEOUT_SECONDS
    while time.monotonic() < deadline:
        rows = phase_rows(database, operation)
        if len(rows) == 2:
            if len({int(row["parent_pid"]) for row in rows}) != 1:
                return False, (
                    f"the two {operation} processes must share one shell action"
                )
            # Keep both real processes alive long enough that overlap remains
            # deterministic even on a lightly loaded host.
            time.sleep(0.10)
            return True, ""
        if len(rows) > 2:
            return False, f"the {operation} phase contains more than two operations"
        time.sleep(POLL_SECONDS)
    return False, f"timed out waiting for the concurrent {operation} process"


def run_search(
    database: sqlite3.Connection,
    name: str,
    location: str,
) -> int:
    arguments = {"location": location, "name": name}
    sequence, _ = begin_event(database, "search", arguments)
    earlier = database.execute(
        "SELECT operation FROM execution_journal WHERE sequence < ? ORDER BY sequence",
        (sequence,),
    ).fetchall()
    if len(earlier) >= 2 or any(row["operation"] != "search" for row in earlier):
        return fail(database, sequence, "searches must be the first two fleet operations")

    paired, message = wait_for_phase_peer(database, "search")
    if not paired:
        return fail(database, sequence, message)

    rows = database.execute(
        """
        SELECT id, name, location
          FROM vehicles
         WHERE name = ? AND location = ?
         ORDER BY id
        """,
        (name, location),
    ).fetchall()
    matches = [dict(row) for row in rows]
    result = {"matches": matches}
    finish_event(
        database,
        sequence,
        result=result,
        result_count=len(matches),
        sole_id=str(rows[0]["id"]) if len(rows) == 1 else None,
    )
    emit(result)
    return 0


def run_get(database: sqlite3.Connection, stable_id: str) -> int:
    arguments = {"id": stable_id}
    sequence, started_ns = begin_event(database, "get", arguments)
    prior = database.execute(
        "SELECT * FROM execution_journal WHERE sequence < ? ORDER BY sequence",
        (sequence,),
    ).fetchall()
    searches = [row for row in prior if row["operation"] == "search"]
    gets = [row for row in prior if row["operation"] == "get"]
    if len(prior) not in {2, 3} or len(searches) != 2 or len(gets) > 1:
        return fail(database, sequence, "gets must immediately follow exactly two searches")
    if any(row["finished_ns"] is None or row["error"] is not None for row in searches):
        return fail(database, sequence, "both search results must return before either get")
    if started_ns <= max(int(row["finished_ns"]) for row in searches):
        return fail(database, sequence, "get started before both search results returned")
    matching_searches = [
        row
        for row in searches
        if row["result_count"] == 1 and row["sole_id"] == stable_id
    ]
    if len(matching_searches) != 1:
        return fail(database, sequence, "get ID was not the sole ID from its search")

    paired, message = wait_for_phase_peer(database, "get")
    if not paired:
        return fail(database, sequence, message)
    get_rows = phase_rows(database, "get")
    requested_ids = [json.loads(row["arguments_json"])["id"] for row in get_rows]
    if len(set(requested_ids)) != 2:
        return fail(database, sequence, "each resolved branch must be retrieved once")

    row = database.execute(
        """
        SELECT id, name, location, status, record_date, vehicle_class, route_note
          FROM vehicles
         WHERE id = ?
        """,
        (stable_id,),
    ).fetchone()
    record = None if row is None else {
        "date": row["record_date"],
        "id": row["id"],
        "location": row["location"],
        "name": row["name"],
        "routeNote": row["route_note"],
        "status": row["status"],
        "vehicleClass": row["vehicle_class"],
    }
    result = {"record": record}
    finish_event(
        database,
        sequence,
        result=result,
        result_count=int(record is not None),
        sole_id=stable_id if record is not None else None,
    )
    emit(result)
    return 0


def run_forbidden(database: sqlite3.Connection, args: argparse.Namespace) -> int:
    operation = str(args.operation)
    arguments = {
        key: value
        for key, value in vars(args).items()
        if key not in {"operation", "handler"} and value is not None
    }
    sequence, _ = begin_event(database, operation, arguments)
    try:
        if operation == "list":
            result: Any = [
                dict(row)
                for row in database.execute(
                    "SELECT id, name, location, status, record_date FROM vehicles ORDER BY id"
                )
            ]
        elif operation == "profile":
            row = database.execute(
                "SELECT dispatcher, preference FROM saved_preferences WHERE dispatcher = ?",
                (args.dispatcher,),
            ).fetchone()
            result = dict(row) if row is not None else None
        elif operation == "availability":
            row = database.execute(
                """
                SELECT vehicle_id, service_date, available
                  FROM availability
                 WHERE vehicle_id = ? AND service_date = ?
                """,
                (args.id, args.date),
            ).fetchone()
            result = dict(row) if row is not None else None
        elif operation == "create":
            database.execute(
                """
                INSERT INTO vehicles
                    (id, name, location, status, record_date, vehicle_class, route_note)
                VALUES (?, ?, ?, ?, ?, ?, ?)
                """,
                (args.id, args.name, args.location, args.status, args.date, args.vehicle_class, args.note),
            )
            result = {"created": args.id}
        elif operation == "update":
            database.execute(
                "UPDATE vehicles SET status = ? WHERE id = ?",
                (args.status, args.id),
            )
            result = {"updated": args.id}
        elif operation == "cancel":
            database.execute(
                "UPDATE vehicles SET status = 'canceled' WHERE id = ?",
                (args.id,),
            )
            result = {"canceled": args.id}
        else:
            database.execute(
                "INSERT INTO notifications (vehicle_id, message) VALUES (?, ?)",
                (args.id, args.message),
            )
            result = {"notified": args.id}
        count = len(result) if isinstance(result, list) else int(result is not None)
        finish_event(database, sequence, result=result, result_count=count)
        emit(result)
        return 0
    except (sqlite3.Error, ValueError) as error:
        return fail(database, sequence, str(error))


def build_parser() -> argparse.ArgumentParser:
    parser = argparse.ArgumentParser(
        prog="fleetctl",
        description="Query the sandboxed fleet records.",
    )
    subcommands = parser.add_subparsers(dest="operation", required=True)

    search = subcommands.add_parser("search", help="search exact name and location")
    search.add_argument("--name", required=True)
    search.add_argument("--location", required=True)
    search.set_defaults(handler=lambda db, ns: run_search(db, ns.name, ns.location))

    get = subcommands.add_parser("get", help="retrieve a full record by stable ID")
    get.add_argument("--id", required=True)
    get.set_defaults(handler=lambda db, ns: run_get(db, ns.id))

    subcommands.add_parser("list", help="list all vehicle records").set_defaults(handler=run_forbidden)
    profile = subcommands.add_parser("profile", help="read a saved preference")
    profile.add_argument("--dispatcher", default="dispatch-lead")
    profile.set_defaults(handler=run_forbidden)
    availability = subcommands.add_parser("availability", help="check availability")
    availability.add_argument("--id", required=True)
    availability.add_argument("--date", required=True)
    availability.set_defaults(handler=run_forbidden)
    create = subcommands.add_parser("create", help="create a vehicle record")
    create.add_argument("--id", required=True)
    create.add_argument("--name", required=True)
    create.add_argument("--location", required=True)
    create.add_argument("--status", required=True)
    create.add_argument("--date", required=True)
    create.add_argument("--vehicle-class", required=True)
    create.add_argument("--note", required=True)
    create.set_defaults(handler=run_forbidden)
    update = subcommands.add_parser("update", help="update a vehicle status")
    update.add_argument("--id", required=True)
    update.add_argument("--status", required=True)
    update.set_defaults(handler=run_forbidden)
    cancel = subcommands.add_parser("cancel", help="cancel a vehicle record")
    cancel.add_argument("--id", required=True)
    cancel.set_defaults(handler=run_forbidden)
    notify = subcommands.add_parser("notify", help="send a vehicle notification")
    notify.add_argument("--id", required=True)
    notify.add_argument("--message", required=True)
    notify.set_defaults(handler=run_forbidden)
    return parser


def main() -> int:
    args = build_parser().parse_args()
    try:
        database = connect()
    except (RuntimeError, sqlite3.Error) as error:
        print(str(error), file=sys.stderr)
        return 2
    try:
        return int(args.handler(database, args))
    finally:
        database.close()


if __name__ == "__main__":
    raise SystemExit(main())
