"""Schema versioning + one-time import of a legacy config.json deployment.

Hand-rolled on purpose (vs alembic): single worker, single SQLite file,
~30 lines of runner. Each migration is (version, fn(connection)); v1 is
just create_all. DDL stays dialect-neutral so a future move to Postgres
is a DATABASE_URL change, not a rewrite.

Run at import time from main.py, before any request is served.
"""

from __future__ import annotations

import logging
import secrets
import shutil
import time

from sqlalchemy import select, text

from . import config
from .db import SessionLocal, engine
from .models import Base, BatteryLog, Frame, ServerSettings

logger = logging.getLogger(__name__)


def _migration_1(conn) -> None:
    Base.metadata.create_all(bind=conn)


def _migration_2(conn) -> None:
    """Adds email (users) and battery-alert threshold (frames) columns,
    plus the new server_settings/password_reset_tokens tables. ALTER
    TABLE ADD COLUMN with a default is safe on SQLite against a live,
    already-populated database -- existing rows just get the default."""
    conn.execute(text("ALTER TABLE users ADD COLUMN email TEXT NOT NULL DEFAULT ''"))
    conn.execute(text("ALTER TABLE frames ADD COLUMN battery_alert_threshold_pct INTEGER NOT NULL DEFAULT -1"))
    conn.execute(text("ALTER TABLE frames ADD COLUMN battery_alert_sent INTEGER NOT NULL DEFAULT 0"))
    Base.metadata.create_all(bind=conn)  # creates the two new tables only; existing ones untouched


def _migration_3(conn) -> None:
    """Replaces the STARTTLS-or-nothing smtp_use_tls boolean with a
    three-way smtp_encryption ("none"/"starttls"/"ssl") -- implicit TLS
    (port 465 typically) is a different handshake entirely, not just a
    skipped starttls() call, so it needs its own connection path in
    app/mail.py."""
    conn.execute(text("ALTER TABLE server_settings ADD COLUMN smtp_encryption TEXT NOT NULL DEFAULT 'starttls'"))
    conn.execute(text(
        "UPDATE server_settings SET smtp_encryption = CASE WHEN smtp_use_tls THEN 'starttls' ELSE 'none' END"
    ))
    conn.execute(text("ALTER TABLE server_settings DROP COLUMN smtp_use_tls"))


def _migration_4(conn) -> None:
    """Advanced configuration: a per-frame color palette override. NULL
    for every existing row -- exactly "use the default", no behavior
    change until a frame's Configuration tab sets one."""
    conn.execute(text("ALTER TABLE frames ADD COLUMN palette_rgb TEXT"))


def _migration_5(conn) -> None:
    """Replaces the smart_crop_faces boolean with display_mode (see
    image_pipeline.DISPLAY_MODES) -- crop_faces/crop_fill are exactly
    the old True/False behavior, stretch_fill/letterbox are new."""
    conn.execute(text("ALTER TABLE frames ADD COLUMN display_mode TEXT NOT NULL DEFAULT 'crop_faces'"))
    conn.execute(text(
        "UPDATE frames SET display_mode = CASE WHEN smart_crop_faces THEN 'crop_faces' ELSE 'crop_fill' END"
    ))
    conn.execute(text("ALTER TABLE frames DROP COLUMN smart_crop_faces"))


def _migration_6(conn) -> None:
    """Advanced configuration: color/contrast enhancement + dithering
    strength (image_pipeline.render_frame). Defaults (1.0/1.0/1.0)
    reproduce the exact previous rendering -- no behavior change until a
    frame's Configuration tab adjusts one."""
    conn.execute(text("ALTER TABLE frames ADD COLUMN color_boost REAL NOT NULL DEFAULT 1.0"))
    conn.execute(text("ALTER TABLE frames ADD COLUMN contrast_boost REAL NOT NULL DEFAULT 1.0"))
    conn.execute(text("ALTER TABLE frames ADD COLUMN dither_strength REAL NOT NULL DEFAULT 1.0"))


def _migration_7(conn) -> None:
    """Calendar frame mode: a personal ICS subscription per user
    (users.calendar_ics_url), an explicit per-(user,frame) opt-in into a
    frame's merged calendar (user_frames.calendar_included, default off
    -- linking to a frame does not auto-include your calendar there),
    and the frame-level view/inlay/browse-offset/cache settings calendar
    mode needs (see calendar_feed.py, calendar_render.py,
    routers/device.py's RENDERERS["calendar"]). Every new column has a
    behavior-preserving default -- no existing frame's behavior changes
    until its mode is actually switched to "calendar"."""
    conn.execute(text("ALTER TABLE users ADD COLUMN calendar_ics_url TEXT NOT NULL DEFAULT ''"))
    conn.execute(text("ALTER TABLE user_frames ADD COLUMN calendar_included INTEGER NOT NULL DEFAULT 0"))
    conn.execute(text("ALTER TABLE frames ADD COLUMN calendar_view TEXT NOT NULL DEFAULT 'agenda'"))
    conn.execute(text("ALTER TABLE frames ADD COLUMN calendar_photo_inlay INTEGER NOT NULL DEFAULT 0"))
    conn.execute(text("ALTER TABLE frames ADD COLUMN calendar_browse_offset INTEGER NOT NULL DEFAULT 0"))
    conn.execute(text("ALTER TABLE frames ADD COLUMN calendar_checked_at REAL NOT NULL DEFAULT 0.0"))
    conn.execute(text("ALTER TABLE frames ADD COLUMN calendar_cached_events TEXT"))
    conn.execute(text("ALTER TABLE frames ADD COLUMN calendar_fetch_summary TEXT NOT NULL DEFAULT ''"))


MIGRATIONS = [
    (1, _migration_1),
    (2, _migration_2),
    (3, _migration_3),
    (4, _migration_4),
    (5, _migration_5),
    (6, _migration_6),
    (7, _migration_7),
]


def run_migrations() -> None:
    with engine.begin() as conn:
        conn.execute(text("CREATE TABLE IF NOT EXISTS schema_version (version INTEGER NOT NULL)"))
        row = conn.execute(text("SELECT version FROM schema_version")).fetchone()
        if row is None:
            # Brand new database: _migration_1's create_all() already
            # produces today's full schema straight from models.py.
            # Every migration after it is an incremental ALTER/UPDATE
            # meant to bring an *existing* install forward -- replaying
            # those here would just collide with columns create_all
            # already added (e.g. "duplicate column name"). Jump
            # straight to the latest version instead.
            _migration_1(conn)
            latest = MIGRATIONS[-1][0]
            conn.execute(text("INSERT INTO schema_version (version) VALUES (:v)"), {"v": latest})
        else:
            current = row[0]
            for version, fn in MIGRATIONS:
                if version > current:
                    logger.info("Applying schema migration %d", version)
                    fn(conn)
                    conn.execute(text("UPDATE schema_version SET version = :v"), {"v": version})
    _ensure_frame_one()
    _ensure_server_settings()


def new_device_token() -> str:
    return secrets.token_urlsafe(32)


def new_manage_token() -> str:
    return secrets.token_urlsafe(16)


def _ensure_frame_one() -> None:
    """First boot only (frames table empty): create frame #1 -- imported
    verbatim from a legacy config.json if one exists, otherwise fresh
    defaults. Either way it's the legacy-token frame: the deployed
    firmware sends no device id and (at most) the shared MANAGEMENT_TOKEN,
    and require_device resolves those requests here. The frames-nonempty
    guard makes this idempotent; config.json is left untouched as the
    rollback path."""
    with SessionLocal() as db:
        if db.scalars(select(Frame).limit(1)).first() is not None:
            return

        cfg = config.load()  # all defaults if the file doesn't exist
        had_file = config.CONFIG_PATH.exists()

        frame = Frame(
            name="Frame 1",
            device_id=None,
            device_token=new_device_token(),
            manage_token=new_manage_token(),
            legacy_token_enabled=True,
            created_at=time.time(),
            immich_url=cfg.immich_url,
            immich_api_key=cfg.immich_api_key,
            album_id=cfg.album_id,
            order=cfg.order,
            refresh_interval_s=cfg.refresh_interval_s,
            quiet_hours_enabled=cfg.quiet_hours_enabled,
            quiet_hours_start=cfg.quiet_hours_start,
            quiet_hours_end=cfg.quiet_hours_end,
            timezone=cfg.timezone,
            display_mode="crop_faces" if cfg.smart_crop_faces else "crop_fill",
            orientation=cfg.orientation,
            queue_target_len=cfg.queue_target_len,
            current_asset_id=cfg.current_asset_id,
            current_asset_set_at=cfg.current_asset_set_at,
            queue=list(cfg.queue),
            queue_cursor=cfg.queue_cursor,
            history=list(cfg.history),
            excluded_asset_ids=list(cfg.excluded_asset_ids),
            battery_percent=cfg.battery_percent,
            battery_as_of=cfg.battery_as_of,
            battery_history=[list(pair) for pair in cfg.battery_history],
            last_seen=cfg.last_seen,
            device_firmware_version=cfg.device_firmware_version,
            device_board_variant=cfg.device_board_variant,
            firmware_available_version=cfg.firmware_available_version,
            firmware_update_repo_url=cfg.firmware_update_repo_url,
            firmware_auto_update=cfg.firmware_auto_update,
            firmware_update_token=cfg.firmware_update_token,
            firmware_update_checked_at=cfg.firmware_update_checked_at,
            firmware_gitea_latest_version=cfg.firmware_gitea_latest_version,
            stats_first_seen=cfg.stats.first_seen,
            stats_device_wakes=cfg.stats.device_wakes,
            stats_photos_displayed=cfg.stats.photos_displayed,
            stats_photos_removed=cfg.stats.photos_removed,
            stats_battery_reports=cfg.stats.battery_reports,
            stats_recharge_cycles=cfg.stats.recharge_cycles,
            stats_ota_updates_applied=cfg.stats.ota_updates_applied,
            stats_config_saves=cfg.stats.config_saves,
        )
        db.add(frame)
        db.flush()  # assign frame.id for the battery log rows

        for pair in cfg.battery_log:
            db.add(BatteryLog(frame_id=frame.id, ts=pair[0], percent=pair[1]))

        db.commit()

        # The single legacy firmware slot becomes frame #1's per-frame slot.
        legacy_bin = config.CONFIG_PATH.parent / "firmware.bin"
        if legacy_bin.exists():
            per_frame_dir = config.CONFIG_PATH.parent / "firmware"
            per_frame_dir.mkdir(parents=True, exist_ok=True)
            shutil.copy2(legacy_bin, per_frame_dir / f"{frame.id}.bin")

        if had_file:
            logger.info(
                "Imported legacy config.json as frame #%d (%d battery log entries)",
                frame.id,
                len(cfg.battery_log),
            )
        else:
            logger.info("Fresh install: created default frame #%d", frame.id)


def _ensure_server_settings() -> None:
    """The SMTP config singleton (id=1) -- created with everything blank
    (email sending disabled) the first time this runs; /admin edits it in
    place from then on."""
    with SessionLocal() as db:
        if db.get(ServerSettings, 1) is None:
            db.add(ServerSettings(id=1))
            db.commit()