#!/usr/bin/env python3
# SPDX-License-Identifier: GPL-3.0-or-later
"""scenarios.py -- the on-device performance scenarios.

Each scenario drives LibreMail through the guarded :class:`adb.Adb` wrapper, times the
behaviour primarily from the on-device breadcrumbs (with uiautomator as a fallback ready
signal), and returns render-ready samples for :mod:`report`.

Timing philosophy (from the manual run): message-open and reader-ready times come from the
``MailReader`` / ``Reader`` / ``ImapPerf`` breadcrumbs -- adb UI polling only tells us *when*
the content is ready so we can move on, and back-nav is explicitly dump-latency-bound.

Safety: every device call goes through :class:`adb.Adb`, so its allow/deny guardrails apply.
Every uiautomator/input step is guarded against the keyguard and against a foreign app being
in the foreground; a sample taken against either is skipped, not measured.

``--dry-run`` executes one representative pass per scenario -- issuing the canonical command
sequence (so the plan is auditable) without looping on a live UI.
"""

from __future__ import annotations

import os
import time
from typing import Callable, List, Optional

import breadcrumbs
import uidump
from adb import Adb, parse_am_start
from report import BackNavSample, ColdOpenSample, ReaderOpenRow

# Message-open can stall 30-75 s behind the spinner (Gmail throttle), so allow generous
# headroom before giving up on a single open.
OPEN_TIMEOUT_S = 150.0
POLL_INTERVAL_S = 2.0
SETTLE_S = 1.5

# Fetch-policy option labels (from res/values/strings.xml) used to drive the A/B toggle.
FETCH_WIFI_LABEL = "Fetch all on Wi-Fi"       # prefetch ON  (Condition A / WIFI_ONLY)
FETCH_ON_DEMAND_LABEL = "Always on-demand"    # prefetch OFF (Condition B / ON_DEMAND)


# --------------------------------------------------------------------------- #
# Live-logcat tailing (per-sample breadcrumb extraction)
# --------------------------------------------------------------------------- #
class LogTailer:
    """Reads newly-appended text from the growing session logcat file since the last mark."""

    def __init__(self, path: str) -> None:
        self.path = path
        self._offset = 0

    def mark(self) -> None:
        """Set the read cursor to the current end of file."""
        self._offset = os.path.getsize(self.path) if os.path.exists(self.path) else 0

    def read_new(self) -> str:
        if not os.path.exists(self.path):
            return ""
        with open(self.path, "r", encoding="utf-8", errors="replace") as fh:
            fh.seek(self._offset)
            data = fh.read()
            self._offset = fh.tell()
        return data


class _NullTailer(LogTailer):
    """A tailer that yields nothing -- used in dry-run so scenarios need no live log."""

    def __init__(self) -> None:  # noqa: D401 - see base
        super().__init__(path="")

    def mark(self) -> None:
        pass

    def read_new(self) -> str:
        return ""


# --------------------------------------------------------------------------- #
# UI helpers (all guarded)
# --------------------------------------------------------------------------- #
def dump_ui(adb: Adb) -> Optional[uidump.UiNode]:
    """Dump + parse the current UI; ``None`` in dry-run or on an unparseable dump."""
    if adb.dry_run:
        return None
    xml = adb.uiautomator_dump()
    if not xml or "<hierarchy" not in xml:
        return None
    try:
        return uidump.parse_dump(xml)
    except Exception:  # pragma: no cover - malformed dump under load
        return None


def ensure_awake(adb: Adb, log: Callable[[str], None]) -> None:
    """Keep the screen on and awake for the run (restored by the caller afterwards)."""
    adb.stay_on(True)
    adb.wake()


def guard_ready(adb: Adb, package: str, log: Callable[[str], None]) -> Optional[uidump.UiNode]:
    """Return the current UI iff it is our app and not the keyguard; else try to recover.

    Returns ``None`` if, after a wake attempt, the sample is still against the lockscreen or
    a foreign app -- the caller must skip that sample rather than measure garbage.
    """
    root = dump_ui(adb)
    if root is None:
        return None
    if uidump.is_lockscreen(root):
        log("keyguard detected; waking and re-checking")
        adb.wake()
        time.sleep(SETTLE_S)
        root = dump_ui(adb)
        if root is None or uidump.is_lockscreen(root):
            log("still on keyguard after wake; skipping sample")
            return None
    if not uidump.is_app_foreground(root, package):
        log(f"foreground is {uidump.foreground_package(root)!r}, not {package!r}; skipping")
        return None
    return root


def goto_mailbox(adb: Adb, package: str, log: Callable[[str], None]) -> Optional[uidump.UiNode]:
    """Ensure the mailbox list is showing (press Back out of the reader if needed)."""
    root = guard_ready(adb, package, log)
    if root is None:
        return None
    if uidump.is_reader(root, package):
        adb.input_keyevent("KEYCODE_BACK")
        time.sleep(SETTLE_S)
        root = guard_ready(adb, package, log)
    return root


def wait_for_reader_ready(adb: Adb, package: str, log: Callable[[str], None]) -> bool:
    """Poll until the reader has loaded its body (no spinner) or timeout. True if loaded."""
    deadline = time.monotonic() + OPEN_TIMEOUT_S
    while time.monotonic() < deadline:
        time.sleep(POLL_INTERVAL_S)
        root = dump_ui(adb)
        if root is None:
            continue
        if uidump.is_lockscreen(root):
            log("keyguard appeared during open; sample is invalid")
            return False
        if uidump.is_reader(root, package) and not uidump.has_progress_bar(root):
            return True
    log("open timed out")
    return False


# --------------------------------------------------------------------------- #
# Scenario 1: cold open
# --------------------------------------------------------------------------- #
def cold_open(
    adb: Adb,
    component: str,
    runs: int,
    log: Callable[[str], None],
    settle_s: float = 2.0,
) -> List[ColdOpenSample]:
    """Force-stop + clear cache + ``am start -W`` x ``runs``; parse TotalTime/WaitTime."""
    samples: List[ColdOpenSample] = []
    for run in range(1, runs + 1):
        adb.force_stop()
        adb.clear_cache()
        adb.settle(settle_s)
        out = adb.start_activity(component=component, wait=True).stdout
        fields = parse_am_start(out)
        note = "" if fields else ("dry-run" if adb.dry_run else "no am-start timing parsed")
        samples.append(
            ColdOpenSample(
                run=run,
                total_time_ms=fields.get("TotalTime"),
                wait_time_ms=fields.get("WaitTime"),
                note=note,
            )
        )
        log(f"cold-open run {run}: {fields or note}")
        adb.settle(settle_s)
    return samples


# --------------------------------------------------------------------------- #
# Scenario 2: message open (uncached)
# --------------------------------------------------------------------------- #
def _row_from_events(index: int, label: str, events: List[breadcrumbs.Event]) -> ReaderOpenRow:
    """Build a reader-open row from the breadcrumbs captured during one open."""
    opens = breadcrumbs.correlate_opens(events)
    if not opens:
        return ReaderOpenRow(index=index, label=label, skipped=True, reason="no breadcrumb")
    sample = opens[-1]
    return ReaderOpenRow.from_open_sample(sample, index=index, label=label)


def open_one_message(
    adb: Adb,
    package: str,
    tailer: LogTailer,
    index: int,
    already_opened: set,
    log: Callable[[str], None],
) -> Optional[ReaderOpenRow]:
    """Open the next not-yet-opened, uncached message; return its timed row (or ``None``)."""
    root = goto_mailbox(adb, package, log)
    if root is None:
        return ReaderOpenRow(index=index, label="?", skipped=True, reason="not on mailbox")

    rows = uidump.find_message_rows(root, package)
    candidates = [r for r in rows if not r.cached and r.label not in already_opened]
    if not candidates:
        # Scroll to reveal more of the list, then re-scan once.
        adb.input_swipe(672, 2000, 672, 900, 400)
        time.sleep(SETTLE_S)
        root = guard_ready(adb, package, log)
        if root is None:
            return None
        rows = uidump.find_message_rows(root, package)
        candidates = [r for r in rows if not r.cached and r.label not in already_opened]
    if not candidates:
        log("no more uncached messages visible")
        return None

    target = candidates[0]
    already_opened.add(target.label)
    log(f"opening row#{target.index} {target.label!r} at {target.center}")

    tailer.mark()
    adb.input_tap(*target.center)
    loaded = wait_for_reader_ready(adb, package, log)
    events = list(breadcrumbs.iter_events(tailer.read_new().splitlines()))
    row = _row_from_events(index, target.label, events)
    if not loaded and not row.skipped:
        row.reason = "ui ready-signal timed out (breadcrumb used)"
    elif not loaded:
        row.skipped = True
        row.reason = "open timed out"
    # Return to the mailbox for the next sample.
    adb.input_keyevent("KEYCODE_BACK")
    time.sleep(SETTLE_S)
    return row


def message_open(
    adb: Adb,
    package: str,
    tailer: LogTailer,
    count: int,
    log: Callable[[str], None],
) -> List[ReaderOpenRow]:
    """Open up to ``count`` distinct uncached messages one at a time."""
    if adb.dry_run:
        _dry_run_open_demo(adb, log)
        return [ReaderOpenRow(index=1, label="<dry-run>", skipped=True, reason="dry-run")]

    rows: List[ReaderOpenRow] = []
    opened: set = set()
    for i in range(1, count + 1):
        row = open_one_message(adb, package, tailer, i, opened, log)
        if row is None:
            break
        rows.append(row)
    return rows


def _dry_run_open_demo(adb: Adb, log: Callable[[str], None]) -> None:
    """Issue the canonical message-open command shape once (dry-run only)."""
    adb.uiautomator_dump()
    adb.input_tap(672, 504)          # tap a representative message row centre
    adb.input_keyevent("KEYCODE_BACK")


# --------------------------------------------------------------------------- #
# Scenario 3: back navigation
# --------------------------------------------------------------------------- #
def back_nav(
    adb: Adb,
    package: str,
    count: int,
    log: Callable[[str], None],
) -> List[BackNavSample]:
    """Time reader -> mailbox back transitions (dump-latency-bound; see report caveat)."""
    if adb.dry_run:
        adb.uiautomator_dump()
        adb.input_keyevent("KEYCODE_BACK")
        return [BackNavSample(index=1, back_ms=None, note="dry-run")]

    samples: List[BackNavSample] = []
    opened: set = set()
    for i in range(1, count + 1):
        # Get into the reader by opening any message.
        root = goto_mailbox(adb, package, log)
        if root is None:
            samples.append(BackNavSample(index=i, back_ms=None, note="not on mailbox"))
            continue
        rows = uidump.find_message_rows(root, package)
        if not rows:
            samples.append(BackNavSample(index=i, back_ms=None, note="no rows"))
            continue
        adb.input_tap(*rows[0].center)
        wait_for_reader_ready(adb, package, log)
        # Now time the back transition to the mailbox.
        start = time.monotonic()
        adb.input_keyevent("KEYCODE_BACK")
        reached = _wait_until(
            lambda: _is_mailbox(adb, package), timeout_s=30.0
        )
        elapsed_ms = round((time.monotonic() - start) * 1000)
        samples.append(
            BackNavSample(
                index=i,
                back_ms=elapsed_ms if reached else None,
                note="" if reached else "did not reach mailbox",
            )
        )
    return samples


def _is_mailbox(adb: Adb, package: str) -> bool:
    root = dump_ui(adb)
    return root is not None and uidump.is_app_foreground(root, package) and not uidump.is_reader(
        root, package
    )


def _wait_until(predicate: Callable[[], bool], timeout_s: float) -> bool:
    deadline = time.monotonic() + timeout_s
    while time.monotonic() < deadline:
        if predicate():
            return True
        time.sleep(0.2)
    return False


# --------------------------------------------------------------------------- #
# Scenario 4: prefetch A/B (fetch policy toggle)
# --------------------------------------------------------------------------- #
def set_fetch_policy(
    adb: Adb,
    package: str,
    option_label: str,
    log: Callable[[str], None],
) -> bool:
    """Navigate Settings and select a fetch-policy option by its visible label.

    NOTE: no uiautomator dump of the settings screen was captured in the manual run, so the
    settings-screen navigation is by on-screen text and needs live verification (documented
    in the README). Returns True if the option was found and tapped.
    """
    if adb.dry_run:
        adb.uiautomator_dump()
        adb.input_tap(1014, 2728)   # bottom-nav "Settings"
        adb.uiautomator_dump()
        adb.input_tap(672, 1400)    # representative fetch-policy option
        adb.input_keyevent("KEYCODE_BACK")
        return True

    root = goto_mailbox(adb, package, log)
    if root is None:
        return False
    settings_label = uidump.find_by_text(root, "Settings")
    if settings_label is None:
        log("no Settings entry found in bottom nav")
        return False
    anchor = settings_label.first_clickable_ancestor() or settings_label
    if anchor.center:
        adb.input_tap(*anchor.center)
    time.sleep(SETTLE_S)

    # Find the fetch-policy option, scrolling the settings list if necessary.
    for _ in range(6):
        sroot = guard_ready(adb, package, log)
        if sroot is None:
            return False
        option = uidump.find_by_text(sroot, option_label)
        if option is not None:
            anchor = option.first_clickable_ancestor() or option
            if anchor.center:
                adb.input_tap(*anchor.center)
                log(f"selected fetch policy {option_label!r}")
                time.sleep(SETTLE_S)
                adb.input_keyevent("KEYCODE_BACK")  # back to mailbox
                time.sleep(SETTLE_S)
                return True
        adb.input_swipe(672, 2000, 672, 900, 400)
        time.sleep(SETTLE_S)
    log(f"fetch-policy option {option_label!r} not found")
    return False


def prefetch_ab(
    adb: Adb,
    package: str,
    component: str,
    tailer: LogTailer,
    count: int,
    log: Callable[[str], None],
) -> dict:
    """Run message-open under prefetch ON (Wi-Fi) vs OFF (on-demand), cache cleared between."""
    result = {"conditionA": [], "conditionB": []}

    log("Condition A: fetch policy = Fetch all on Wi-Fi (prefetch ON)")
    set_fetch_policy(adb, package, FETCH_WIFI_LABEL, log)
    _reset_for_uncached(adb, component, log)
    result["conditionA"] = message_open(adb, package, tailer, count, log)

    log("Condition B: fetch policy = Always on-demand (prefetch OFF)")
    set_fetch_policy(adb, package, FETCH_ON_DEMAND_LABEL, log)
    _reset_for_uncached(adb, component, log)
    result["conditionB"] = message_open(adb, package, tailer, count, log)
    return result


def _reset_for_uncached(adb: Adb, component: str, log: Callable[[str], None]) -> None:
    """Clear the cache (and restart) so subsequent opens are uncached network fetches."""
    adb.force_stop()
    adb.clear_cache()
    adb.settle(1.0)
    adb.start_activity(component=component, wait=True)
    adb.settle(3.0)


# --------------------------------------------------------------------------- #
# Scenario 5: cross-provider (optional)
# --------------------------------------------------------------------------- #
def cross_provider(
    adb: Adb,
    package: str,
    tailer: LogTailer,
    count: int,
    log: Callable[[str], None],
) -> dict:
    """Open ``count`` messages from the (unified) inbox and bucket the rows by account_ref.

    The breadcrumbs carry the account reference (``imap:...`` vs ``outlook:...``), so a
    single mixed-inbox pass yields the per-provider comparison without account switching.
    """
    rows = message_open(adb, package, tailer, count, log)
    buckets: dict = {}
    for row in rows:
        key = row.account_ref or "unknown"
        buckets.setdefault(key, []).append(row)
    return buckets