"""JSON-file-backed config: Immich connection, selected album, and cursor
state (which photo /frame/image serves next)."""

from __future__ import annotations

import json
import os
from contextlib import contextmanager
from pathlib import Path
from threading import RLock
from typing import Iterator

from pydantic import BaseModel

CONFIG_PATH = Path(os.environ.get("CONFIG_PATH", "/data/config.json"))

# Reentrant so load()/save() can each take it internally for their own I/O
# while a caller also holds it for a whole locked() span (see below).
_lock = RLock()


class FrameStats(BaseModel):
    """Cumulative, lifetime counters -- purely informational, never read
    back to drive any behavior, so there's no harm in them being a little
    approximate at the edges. Shown in a collapsed "Stats" section in the
    web UI (GET /api/stats). Never reset except by deleting config.json."""
    first_seen: float = 0.0  # first time this frame ever checked in
    device_wakes: int = 0  # wake cycles, counted once each via GET /frame/config
    photos_displayed: int = 0  # times the current photo actually changed (any cause)
    photos_removed: int = 0  # times a photo was permanently excluded from rotation
    battery_reports: int = 0  # POST /frame/battery calls
    recharge_cycles: int = 0  # times a battery recharge was detected
    ota_updates_applied: int = 0  # times the device's reported firmware version changed
    config_saves: int = 0  # POST /api/config calls


class FrameConfig(BaseModel):
    immich_url: str = ""
    immich_api_key: str = ""
    management_token: str = ""  # gates the web UI (see main.py); empty = no gate, open on trusted LAN
    album_id: str = ""
    order: str = "sequential"  # or "shuffle"
    refresh_interval_s: int = 3600
    # Quiet hours: no point waking the device overnight just to swap a
    # photo nobody's looking at. Times are "HH:MM" interpreted in
    # `timezone` below and may wrap past midnight (e.g. start=22:00,
    # end=07:00). Purely a server-side decision -- the device is unaware,
    # it just gets told a longer refresh_interval_s by GET /frame/config
    # while quiet hours are in effect (see main.py's
    # _effective_refresh_interval_s).
    quiet_hours_enabled: bool = False
    quiet_hours_start: str = "22:00"
    quiet_hours_end: str = "07:00"
    # IANA zone name (e.g. "America/New_York") quiet_hours_start/end are
    # interpreted in. Set from the web UI rather than the container's TZ
    # environment variable, so it survives container recreation and
    # doesn't need a docker-compose.yml edit to change.
    timezone: str = "UTC"
    smart_crop_faces: bool = True
    # How the physical frame is hung: landscape (native), portrait,
    # landscape_flipped, portrait_flipped. Purely a server-side render
    # decision -- the device always receives native 800x480 bytes.
    orientation: str = "landscape"

    # Current photo + upcoming queue (see app/photo_queue.py). current_asset_set_at
    # is what lets the server decide "has it been long enough to advance" on its
    # own clock, independent of how/why the device asked for a photo.
    current_asset_id: str = ""
    current_asset_set_at: float = 0.0
    queue: list[str] = []
    queue_cursor: int = 0  # internal bookkeeping for sequential queue top-up; not user-facing
    queue_target_len: int = 20  # how many upcoming photos to keep queued/shown in the web UI
    history: list[str] = []  # bounded stack of previously-current asset ids, most recent last
    excluded_asset_ids: list[str] = []  # permanently removed from this frame's rotation (not deleted from Immich)

    # Last battery report from the device (POST /frame/battery); -1 = never
    # reported / not battery-powered. battery_as_of mirrors the
    # current_asset_set_at timestamp pattern.
    battery_percent: int = -1
    battery_as_of: float = 0.0
    # [timestamp, percent] pairs for the CURRENT discharge cycle only --
    # reset whenever a report jumps up enough to indicate a recharge (see
    # main.py). Feeds the "on battery for" and "estimated remaining"
    # numbers in the web UI's Device panel.
    battery_history: list = []
    # Every report ever received, never reset by a recharge -- the
    # permanent record behind the web UI's battery history graph. Capped
    # generously (not a real limit at realistic report rates, just a
    # safety bound), unlike battery_history above which is deliberately
    # scoped to one cycle.
    battery_log: list = []

    # Device liveness/telemetry: last_seen is touched by every /frame/*
    # request; device_firmware_version/device_board_variant come from the
    # X-Frame-Version/X-Frame-Board headers the device sends with its
    # config poll (CONFIG_FRAME_BOARD_NAME on the firmware side).
    last_seen: float = 0.0
    device_firmware_version: str = ""
    device_board_variant: str = ""  # "" until a device has ever checked in
    # Version parsed out of the most recently uploaded OTA image
    # (POST /api/firmware); "" = none uploaded yet.
    firmware_available_version: str = ""

    # Gitea-hosted firmware auto-update (see app/gitea_releases.py).
    # repo_url empty = feature off, no Gitea calls made at all. Which
    # release asset to pull is learned from the device itself
    # (device_board_variant below, from its X-Frame-Board header) rather
    # than picked by the user -- must match one of the names
    # .gitea/workflows/firmware-release-build.yml publishes
    # (firmware-<board_variant>.bin).
    firmware_update_repo_url: str = ""  # e.g. "https://git.example.com/owner/repo"
    firmware_auto_update: bool = False  # pull+stage a newer release with no button click
    # Optional Gitea PAT (read-only access is enough) for a private repo's
    # releases; blank is fine for a public repo. GITEA_FIRMWARE_TOKEN env
    # var overrides, mirroring MANAGEMENT_TOKEN below -- never exposed to
    # the web UI template or any JSON response.
    firmware_update_token: str = ""
    firmware_update_checked_at: float = 0.0  # throttle bookkeeping, see gitea_releases.UPDATE_CHECK_INTERVAL_S
    firmware_gitea_latest_version: str = ""  # latest release's version, from its tag name

    stats: FrameStats = FrameStats()


def load() -> FrameConfig:
    with _lock:
        if not CONFIG_PATH.exists():
            cfg = FrameConfig()
        else:
            cfg = FrameConfig(**json.loads(CONFIG_PATH.read_text()))

    # IMMICH_URL/IMMICH_API_KEY/MANAGEMENT_TOKEN/GITEA_FIRMWARE_TOKEN set in
    # the environment (e.g. docker-compose.yml, see
    # docker-compose.yml.example) take precedence over whatever's saved in
    # CONFIG_PATH, so credentials never need to go through the web UI.
    env_url = os.environ.get("IMMICH_URL")
    env_key = os.environ.get("IMMICH_API_KEY")
    env_token = os.environ.get("MANAGEMENT_TOKEN")
    env_gitea_token = os.environ.get("GITEA_FIRMWARE_TOKEN")
    if env_url:
        cfg.immich_url = env_url
    if env_key:
        cfg.immich_api_key = env_key
    if env_token:
        cfg.management_token = env_token
    if env_gitea_token:
        cfg.firmware_update_token = env_gitea_token

    return cfg


def save(cfg: FrameConfig) -> None:
    with _lock:
        CONFIG_PATH.parent.mkdir(parents=True, exist_ok=True)
        CONFIG_PATH.write_text(cfg.model_dump_json(indent=2))


@contextmanager
def locked() -> Iterator[None]:
    """Serializes an entire load-mutate-save cycle. load()/save() each
    only lock their own I/O, which isn't enough by itself: uvicorn
    dispatches sync routes to a thread pool, so two concurrent requests
    (e.g. the device's own poll landing alongside a web UI edit) can each
    load() the same on-disk state and the second save() silently clobber
    the first's changes. Route handlers that mutate config should wrap
    their whole load/mutate/save span in this."""
    with _lock:
        yield