# Copyright 2026 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Utilities for handling app locking and initial app launch logic."""

import asyncio
from dataclasses import dataclass, field
import re

from artemis.context import AppLaunchResult, ArtemisContext
from artemis.controllers.platform_specific_commands_controller import (
    get_adb_device,
    get_current_foreground_package_async,
)
from artemis.controllers.unified_controller import UnifiedMobileController
from artemis.data_engine.trace import TraceSpan
from artemis.utils.logger import get_logger

logger = get_logger(__name__)


# ``ActivityRecord{<hash> u<user> <package>/<activity> t<task id>}`` as printed by
# ``dumpsys activity activities`` on every line that names an activity.
_ACTIVITY_RECORD_RE = re.compile(
    r"ActivityRecord\{[0-9a-f]+ u\d+ (?P<package>[\w.]+)/(?P<activity>[\w.$]+) t(?P<task>\d+)\}"
)
# ``* Task{<hash> #<id> type=... A=<uid>:<affinity> ... visible=true ...}`` task headers
# (``* TaskRecord{<hash> #<id> A=<affinity> ...}`` on Android 11 and older).
_TASK_HEADER_RE = re.compile(r"^\s*\* Task(?:Record)?\{[0-9a-f]+ #(?P<task>\d+)(?P<attrs>[^}]*)\}")
# Device-side pre-filter: the full dump runs to hundreds of KB on a busy device;
# only the task headers, history entries and resumed-activity lines are parsed.
_FOREGROUND_DUMP_CMD = (
    "dumpsys activity activities | grep -E"
    r" '^ *\* (Task|TaskRecord)\{|^ *\* Hist |ResumedActivity'"
)
# ``* Hist  #<index>: ActivityRecord{...}`` entries; index 0 is the task's base activity.
_HIST_RE = re.compile(r"^\s*\* Hist\s+#(?P<index>\d+): (?P<record>ActivityRecord\{[^}]*\})")
# ``topResumedActivity=ActivityRecord{...}`` (per task, top task first) and the global
# ``ResumedActivity: ActivityRecord{...}`` line; the first one seen is the foreground one.
_RESUMED_RE = re.compile(r"ResumedActivity[:=]\s*(?P<record>ActivityRecord\{[^}]*\})")


@dataclass(frozen=True)
class ForegroundTask:
    """What ``dumpsys activity activities`` says is on top of the display.

    ``resumed_package`` is the package of the resumed activity (what the user sees).
    ``base_package`` is the package of the task's root activity (``Hist #0``), and
    ``packages`` holds every package that has an activity in that task, so an app whose
    task currently shows a helper activity from another package (Settings search,
    permission dialogs, account pickers, system update pages, ...) is still
    recognised as the foreground app.
    """

    task_id: int | None = None
    affinity: str | None = None
    resumed_component: str | None = None
    resumed_package: str | None = None
    base_package: str | None = None
    packages: frozenset[str] = field(default_factory=frozenset)

    def owns(self, app_package: str) -> bool:
        """Whether ``app_package`` is the app the foreground task belongs to.

        The task affinity is the app's own claim on the task (by default the
        package name, or a package-prefixed name such as
        ``com.android.settings.root``); it stays with the task even when the
        app's root activity has been destroyed and only a companion activity
        (e.g. the Settings search UI) remains in the history."""
        affinity = self.affinity or ""
        return (
            app_package == self.resumed_package
            or app_package == self.base_package
            or app_package in self.packages
            or affinity == app_package
            or affinity.startswith(app_package + ".")
        )

    def describe(self) -> str:
        task = f"task #{self.task_id}" if self.task_id is not None else "task ?"
        details = [f"base={self.base_package}", f"resumed={self.resumed_component}"]
        if self.affinity:
            details.append(f"affinity={self.affinity}")
        others = sorted(self.packages - {self.base_package, self.resumed_package, None})
        if others:
            details.append(f"also={','.join(others)}")
        return f"{task} ({', '.join(details)})"


def parse_foreground_task(dump: str) -> ForegroundTask | None:
    """Parse ``dumpsys activity activities`` output into the foreground task summary.

    The foreground task is the one holding the resumed activity; when no activity is
    resumed (mid-transition) the first visible task with history entries is used.
    Returns None when the dump contains no task information at all.
    """
    task_attrs: dict[int, str] = {}
    task_order: list[int] = []
    task_activities: dict[int, list[tuple[int, str, str]]] = {}
    resumed: re.Match[str] | None = None

    for line in dump.splitlines():
        header = _TASK_HEADER_RE.match(line)
        if header:
            task_id = int(header.group("task"))
            if task_id not in task_attrs:
                task_attrs[task_id] = header.group("attrs")
                task_order.append(task_id)
            continue
        hist = _HIST_RE.match(line)
        if hist:
            record = _ACTIVITY_RECORD_RE.search(hist.group("record"))
            if record:
                task_activities.setdefault(int(record.group("task")), []).append(
                    (int(hist.group("index")), record.group("package"), record.group("activity"))
                )
            continue
        if resumed is None:
            match = _RESUMED_RE.search(line)
            if match:
                resumed = _ACTIVITY_RECORD_RE.search(match.group("record"))

    if not task_attrs and resumed is None:
        return None

    task_id: int | None = None
    if resumed is not None:
        task_id = int(resumed.group("task"))
    else:
        for candidate in task_order:
            if "visible=true" in task_attrs[candidate] and candidate in task_activities:
                task_id = candidate
                break

    activities = sorted(task_activities.get(task_id, []))
    affinity_match = re.search(r"\bA=(?:\d+:)?(\S+)", task_attrs.get(task_id, ""))
    return ForegroundTask(
        task_id=task_id,
        affinity=affinity_match.group(1) if affinity_match else None,
        resumed_component=(
            f"{resumed.group('package')}/{resumed.group('activity')}" if resumed else None
        ),
        resumed_package=resumed.group("package") if resumed else None,
        base_package=activities[0][1] if activities else None,
        packages=frozenset(package for _, package, _ in activities),
    )


def get_foreground_task(ctx: ArtemisContext) -> ForegroundTask | None:
    """Read the foreground task from ``dumpsys activity activities`` on the device.

    Blocking (a synchronous ADB shell round-trip); async callers go through
    :func:`get_foreground_task_async` so the event loop keeps serving.
    """
    try:
        device = get_adb_device(ctx)
        if device is None:
            return None
        dump = str(device.shell(_FOREGROUND_DUMP_CMD))
        if "Task" not in dump:
            # No grep on the device (or nothing matched): parse the full dump.
            dump = str(device.shell("dumpsys activity activities"))
        return parse_foreground_task(dump)
    except Exception as e:
        logger.debug(f"Failed to retrieve foreground task via dumpsys: {e}")
        return None


async def get_foreground_task_async(ctx: ArtemisContext) -> ForegroundTask | None:
    """:func:`get_foreground_task` off the event loop."""
    return await asyncio.to_thread(get_foreground_task, ctx)


async def _observe_foreground(
    ctx: ArtemisContext, app_package: str
) -> tuple[bool, str | None, ForegroundTask | None]:
    """Report whether ``app_package`` is in the foreground.

    Fast path: the focused window's package equals the target. Otherwise the app also
    counts as foreground when the top task belongs to it (see ``ForegroundTask``).
    A ``None`` focused package means the window manager is mid-transition and is
    reported as "not yet" without consulting the task stack.

    Returns (is_foreground, focused_package, foreground_task); the task is only read
    when the fast path fails on a non-null focused package.
    """
    current_package = await get_current_foreground_package_async(ctx)
    if current_package == app_package:
        return True, current_package, None
    if current_package is None:
        return False, None, None
    task = await get_foreground_task_async(ctx)
    return task is not None and task.owns(app_package), current_package, task


async def _poll_for_app_ready(
    ctx: ArtemisContext,
    app_package: str,
    max_poll_seconds: int = 15,
    poll_interval: float = 1.0,
) -> tuple[bool, str | None]:
    """Poll for app to be ready after launch.

    Treats mCurrentFocus=null as a loading state and keeps polling.
    Only fails if we get a different (non-null) package or timeout.

    Args:
        ctx: Mobile use context
        app_package: Expected package name
        max_poll_seconds: Maximum time to poll (default: 15s)
        poll_interval: Time between polls (default: 1s)

    Returns:
        Tuple of (success: bool, error_message: str | None)
    """
    polls = int(max_poll_seconds / poll_interval)

    for i in range(polls):
        ready, current_package, task = await _observe_foreground(ctx, app_package)

        if ready:
            if current_package == app_package:
                logger.success(f"App {app_package} is ready (took ~{i * poll_interval:.1f}s)")
            else:
                logger.success(
                    f"App {app_package} is ready (focused window belongs to"
                    f" '{current_package}', but the foreground {task.describe()} is owned"
                    f" by {app_package}, took ~{i * poll_interval:.1f}s)"
                )
            return True, None

        if current_package is None:
            logger.debug(f"Poll {i + 1}/{polls}: App loading (mCurrentFocus=null)...")
        else:
            logger.debug(
                f"Poll {i + 1}/{polls}: Wrong app in foreground (expected"
                f" '{app_package}', got '{current_package}', foreground"
                f" {task.describe() if task else 'task unknown'}). Still waiting..."
            )

        if i < polls - 1:
            await asyncio.sleep(poll_interval)

    current_package = await get_current_foreground_package_async(ctx)
    task = await get_foreground_task_async(ctx)
    error_msg = (
        f"Timeout waiting for {app_package} to load after {max_poll_seconds}s. "
        f"Current foreground: {current_package}; foreground"
        f" {task.describe() if task else 'task unknown'}"
    )
    logger.error(error_msg)
    return False, error_msg


async def launch_app_with_retries(
    ctx: ArtemisContext,
    app_package: str,
    max_retries: int = 3,
    max_poll_seconds: int = 15,
) -> tuple[bool, str | None]:
    """Launch an app with retry logic and smart polling.

    Args:
        ctx: Mobile use context
        app_package: Package name (Android) to launch
        max_retries: Maximum number of launch attempts (default: 3)
        max_poll_seconds: Maximum time to wait for app to load per attempt
          (default: 15s)

    Returns:
        Tuple of (success: bool, error_message: str | None)
    """

    for attempt in range(1, max_retries + 1):
        logger.info(f"Launch attempt {attempt}/{max_retries} for app {app_package}")

        with TraceSpan(
            name=f"Launch Attempt {attempt}",
            trace_type="span",
            ctx=ctx,
        ) as span:
            span.payload = {"attempt": attempt, "app_package": app_package}

            controller = UnifiedMobileController(ctx)
            if attempt > 1:
                logger.warning(
                    f"Attempt {attempt - 1} failed. Force stopping"
                    f" '{app_package}' to clear frozen state before retrying..."
                )
                await controller.terminate_app(app_package)
                await asyncio.sleep(1.0)

            launch_success = await controller.launch_app(app_package)
            if not launch_success:
                error_msg = f"Failed to execute launch command for {app_package}"
                logger.error(error_msg)
                span.status = "failed"
                span.error = error_msg
                if attempt == max_retries:
                    return False, error_msg
                await asyncio.sleep(2)
                continue

            await asyncio.sleep(1)

            success, error_msg = await _poll_for_app_ready(ctx, app_package, max_poll_seconds)

            if success:
                span.status = "success"
                span.result = "App is ready"
                return True, None

            span.status = "failed"
            span.error = error_msg

            if attempt < max_retries:
                logger.warning(f"Attempt {attempt} failed: {error_msg}. Retrying...")
                await asyncio.sleep(1)

    error_msg = f"Failed to launch {app_package} after {max_retries} attempts"
    logger.error(error_msg)
    return False, error_msg


async def _handle_initial_app_launch(
    ctx: ArtemisContext,
    locked_app_package: str,
) -> AppLaunchResult:
    """Handle initial app launch verification and launching if needed.

    If locked_app_package is set:
    1. Check if the app is already in the foreground
    2. If not, attempt to launch it (with retries)
    3. Return status with success/error information

    Args:
        ctx: Mobile use context
        locked_app_package: Package name (Android) to lock to

    Returns:
        AppLaunchResult with launch status and error information
    """
    if not locked_app_package:
        error_msg = f"Invalid locked_app_package: '{locked_app_package}'"
        logger.error(error_msg)
        return AppLaunchResult(
            locked_app_package=locked_app_package,
            locked_app_initial_launch_success=False,
            locked_app_initial_launch_error=error_msg,
        )

    logger.info(f"Starting initial app launch for package: {locked_app_package}")

    try:
        already_foreground, current_package, _ = await _observe_foreground(ctx, locked_app_package)
        logger.info(f"Current foreground app: {current_package}")

        if already_foreground:
            logger.info(f"App {locked_app_package} is already in foreground")
            return AppLaunchResult(
                locked_app_package=locked_app_package,
                locked_app_initial_launch_success=True,
                locked_app_initial_launch_error=None,
            )

        logger.info(f"App {locked_app_package} not in foreground, attempting to launch")
        success, error_msg = await launch_app_with_retries(ctx, locked_app_package)

        return AppLaunchResult(
            locked_app_package=locked_app_package,
            locked_app_initial_launch_success=success,
            locked_app_initial_launch_error=error_msg,
        )

    except Exception as e:
        error_msg = f"Exception during initial app launch: {str(e)}"
        logger.error(error_msg)
        return AppLaunchResult(
            locked_app_package=locked_app_package,
            locked_app_initial_launch_success=False,
            locked_app_initial_launch_error=error_msg,
        )