"""Kanta feature demo.

Run from the project root:  python demo/main.py

Demonstrates bootstrap, colored transaction diffs, logfmt value formatting,
custom log headers, logging toggles, rollback, and migrations.  The database
is recreated on every run; everything else lives in this file.
"""

import asyncio
import logging
from pathlib import Path
from types import ModuleType

import msgspec

from kanta import Kanta
from kanta.logging import _ACTION, _ACTOR, _RESET, _SESSION, _TARGET
from kanta.logging import configure_logging

DB = Path(__file__).with_name("demo.db")

# Fake directory: user id -> display name, resolved by the logfmt callbacks.
USERS = {"u1": "Alice", "u2": "Bob", "u3": "Carol"}


class DataV1(msgspec.Struct):
    """Original schema (version 0)."""

    users: dict[str, dict] = {}
    counter: int = 0


class Data(msgspec.Struct):
    """Current schema: migration v1 adds the settings section."""

    users: dict[str, dict] = {}
    counter: int = 0
    settings: dict[str, str] = {}


def migrate_v1(d: dict) -> None:
    """Add settings section"""
    d["settings"] = {"theme": "dark"}


migrations = ModuleType("demo_migrations")
migrations.migrate_v1 = migrate_v1


def add_logfmts(kanta: Kanta) -> None:
    """Resolve user ids to display names in headers and diff paths."""

    @kanta.logfmt(path="$user")
    def resolve_actor(value: str) -> str | None:
        return USERS.get(value)

    @kanta.logfmt
    def resolve_user_key(value: str, path: str) -> str | None:
        if path.startswith("users."):
            return USERS.get(value)
        return None


def add_header(kanta: Kanta) -> None:
    """Aligned rich header: actor, session id, action, target."""

    @kanta.logheader
    def header(action: str, user: str | None, extra: dict | None) -> str:
        actor = f"{_ACTOR}{user or '-':<8}{_RESET}"
        session = f"{_SESSION}{extra.get('session_id', '-'):>2}{_RESET}"
        target = f"{_TARGET}{extra['target']}{_RESET}"
        return f"{actor} {session}  {_ACTION}{action}{_RESET}  {target}"


async def main() -> None:
    DB.unlink(missing_ok=True)

    print("=== Standard logging: bootstrap, diffs, toggles, rollback ===", flush=True)

    kanta = Kanta(DB, DataV1())
    add_logfmts(kanta)

    @kanta.bootstrap
    def seed(data: DataV1) -> None:
        data.users["u1"] = {"name": "Alice", "role": "admin"}

    await kanta.open()

    with kanta.transaction(action="create", user="u2") as data:
        data.users["u2"] = {"name": "Bob", "role": "user"}

    with kanta.transaction(action="update", user="u1") as data:
        data.users["u2"]["role"] = "editor"
        data.counter = 1

    with kanta.transaction(action="delete", user="u1") as data:
        del data.users["u2"]

    # Display-only extra string, appended after the action.
    with kanta.transaction(action="export", user="u1", extra=DB.name) as data:
        data.counter = 2

    # Compact logging: diff only (no header) ...
    with kanta.transaction(
        action="repair", log={"header": False, "diff": True}
    ) as data:
        data.users["u3"] = {"name": "Carol", "role": "user"}

    # A failing transaction rolls back and logs a warning.
    try:
        with kanta.transaction(action="reset", user="u1") as data:
            data.counter = 99
            raise ValueError("simulated failure")
    except ValueError:
        pass

    # ... and header only (no diff).
    with kanta.transaction(
        action="import", user="u1", log={"header": True, "diff": False}
    ) as data:
        data.counter = 3

    await kanta.close()

    print("=== Reopen with migrations and a custom log header ===", flush=True)

    kanta = Kanta(DB, Data(), migrations=migrations)
    add_logfmts(kanta)
    add_header(kanta)
    await kanta.open()

    # No target given: defaults to the database filename.
    with kanta.transaction(action="update", user="u1", extra={"session_id": 3}) as data:
        data.settings["theme"] = "light"

    with kanta.transaction(
        action="update",
        user="u2",
        extra={"session_id": 7, "target": "settings (demo)"},
    ) as data:
        data.settings["lang"] = "en"

    await kanta.close()

    print(f"=== Database written to {DB} ===", flush=True)


if __name__ == "__main__":
    configure_logging()
    logging.getLogger("kanta").setLevel(logging.DEBUG)  # show migration diffs
    asyncio.run(main())