"""Kanban diagnostics — structured, actionable distress signals for tasks.

A ``Diagnostic`` is a machine-readable description of something that's wrong
with a kanban task: a hallucinated card id, a spawn crash-loop, a task
stuck blocked for too long, etc. Each one carries:

* A **kind** (canonical code; UI/tests match on this).
* A **severity** (``warning`` / ``error`` / ``critical``).
* A **title** (one-line human description) and **detail** (longer text).
* A list of **suggested actions** — structured entries the dashboard
  turns into buttons and the CLI turns into hints.

Rules run over (task, recent events, recent runs) and emit diagnostics.
They are stateless and read-only — no DB writes. Callers compute
diagnostics on demand (on ``/board`` load, ``/tasks/:id`` fetch, or
``hermes kanban diagnostics``).

Design goals:

* Fixable-on-the-operator's-side signals only (missing config, phantom
  ids, crash loop). Not "the provider returned 502 once" — that's a
  transient runtime blip, not a diagnostic.
* Recoverable: every diagnostic comes with at least one suggested
  recovery action the operator can actually take from the UI.
* Auto-clearing: when the underlying failure mode resolves (a clean
  ``completed`` event arrives, a spawn succeeds, the task gets
  unblocked), the diagnostic stops firing. The audit event trail stays.
"""

from __future__ import annotations

from dataclasses import dataclass, field
from typing import Any, Callable, Iterable, Optional
import json
import time


# Severity rungs, ordered least → most urgent. The UI colors them
# amber (warning), orange (error), red (critical). Sorted outputs put
# critical first so operators see the worst fires at the top.
SEVERITY_ORDER = ("warning", "error", "critical")


@dataclass
class DiagnosticAction:
    """A single recovery action attached to a diagnostic.

    The ``kind`` determines how both the UI and CLI render it:

    * ``reclaim`` / ``reassign`` — POST to the matching /tasks/:id/*
      endpoint; dashboard wires into the existing recovery popover.
    * ``unblock`` — PATCH status back to ``ready`` (for stuck-blocked
      diagnostics).
    * ``cli_hint`` — print/copy a shell command (e.g.
      ``hermes -p <profile> auth``). No HTTP side effect.
    * ``open_docs`` — deep-link to the docs URL named in ``payload.url``.
    * ``comment`` — nudge the operator to add a comment (for
      stuck-blocked tasks that need human input).

    ``suggested=True`` marks the action as the recommended first step;
    the UI highlights it. Multiple actions can be suggested if they're
    equally valid.
    """

    kind: str
    label: str
    payload: dict = field(default_factory=dict)
    suggested: bool = False

    def to_dict(self) -> dict:
        return {
            "kind": self.kind,
            "label": self.label,
            "payload": self.payload,
            "suggested": self.suggested,
        }


@dataclass
class Diagnostic:
    """One active distress signal on a task."""

    kind: str
    severity: str  # "warning" | "error" | "critical"
    title: str
    detail: str
    actions: list[DiagnosticAction] = field(default_factory=list)
    first_seen_at: int = 0
    last_seen_at: int = 0
    count: int = 1
    # Optional: the run id this diagnostic is scoped to. None = task-wide.
    run_id: Optional[int] = None
    # Optional structured payload for the UI (phantom ids, failure count).
    data: dict = field(default_factory=dict)

    def to_dict(self) -> dict:
        return {
            "kind": self.kind,
            "severity": self.severity,
            "title": self.title,
            "detail": self.detail,
            "actions": [a.to_dict() for a in self.actions],
            "first_seen_at": self.first_seen_at,
            "last_seen_at": self.last_seen_at,
            "count": self.count,
            "run_id": self.run_id,
            "data": self.data,
        }


# ---------------------------------------------------------------------------
# Rule helpers
# ---------------------------------------------------------------------------

def _task_field(task, name, default=None):
    """Read a field from a task regardless of representation.

    Callers pass sqlite3.Row (dict-like with [] but no attribute
    access), kanban_db.Task dataclasses (attribute access), or plain
    dicts (both). This normalises them so rule functions don't have
    to branch on type each time.
    """
    if task is None:
        return default
    # sqlite Row + plain dicts both support mapping access; Row also
    # supports .keys().
    try:
        # Row raises IndexError if the key isn't a column in the query;
        # dicts return default via .get. Handle both.
        if hasattr(task, "keys") and name in task.keys():
            return task[name]
    except Exception:
        pass
    if isinstance(task, dict):
        return task.get(name, default)
    return getattr(task, name, default)


def _parse_payload(ev) -> dict:
    """Tolerate event.payload being either a dict or a JSON string."""
    p = _task_field(ev, "payload", None)
    if p is None:
        return {}
    if isinstance(p, dict):
        return p
    if isinstance(p, str):
        try:
            return json.loads(p) or {}
        except Exception:
            return {}
    return {}


def _event_kind(ev) -> str:
    return _task_field(ev, "kind", "") or ""


def _event_ts(ev) -> int:
    t = _task_field(ev, "created_at", 0)
    return int(t or 0)


def _active_hallucination_events(
    events: Iterable[Any],
    kind: str,
) -> list[Any]:
    """Return events of ``kind`` that have no ``completed``/``edited``
    event *strictly after* them. Walks chronologically: each clean
    event resets the accumulator; each matching event gets appended.

    Events must be sorted by id (i.e. arrival order); callers pass the
    task's full event list which the DB already returns in that order.
    """
    # Events arrive sorted by id asc (chronological). Walk once, track
    # which hallucination events are still "active" (no clean event
    # supersedes them).
    active: list[Any] = []
    for ev in events:
        k = _event_kind(ev)
        if k in ("completed", "edited"):
            active.clear()
        elif k == kind:
            active.append(ev)
    return active


def _latest_clean_event_ts(events: Iterable[Any]) -> int:
    """Timestamp of the most recent clean completion / edit event.

    Kept for general "has this task ever been successfully completed"
    lookups; hallucination rules use ``_active_hallucination_events``
    instead because they need strict ordering.
    """
    latest = 0
    for ev in events:
        if _event_kind(ev) in ("completed", "edited"):
            t = _event_ts(ev)
            if t > latest:
                latest = t
    return latest


# Standard always-available actions. Every diagnostic can offer these as
# fallbacks regardless of kind — they're the two baseline recovery
# primitives the kernel supports.
def _generic_recovery_actions(task: Any, *, running: bool) -> list[DiagnosticAction]:
    out: list[DiagnosticAction] = []
    if running:
        out.append(DiagnosticAction(
            kind="reclaim",
            label="Reclaim task",
            payload={},
        ))
    out.append(DiagnosticAction(
        kind="reassign",
        label="Reassign to different profile",
        payload={"reclaim_first": running},
    ))
    return out


# ---------------------------------------------------------------------------
# Rule implementations
# ---------------------------------------------------------------------------

# Each rule takes (task, events, runs, now_ts, config) and returns
# zero or more Diagnostic instances. ``events`` / ``runs`` are lists of
# kanban_db.Event / kanban_db.Run (or plain dicts matching the same
# shape — for test convenience).

RuleFn = Callable[[Any, list[Any], list[Any], int, dict], list[Diagnostic]]


def _rule_hallucinated_cards(task, events, runs, now, cfg) -> list[Diagnostic]:
    """Blocked-hallucination gate fires: a worker called kanban_complete
    with created_cards that didn't exist or weren't created by the
    completing profile. Task stayed in its prior state; the operator
    needs to decide how to proceed.

    Auto-clears when a successful completion (or edit) follows the
    blocked event.
    """
    hits = _active_hallucination_events(events, "completion_blocked_hallucination")
    if not hits:
        return []
    phantom_ids: list[str] = []
    first = _event_ts(hits[0])
    last = _event_ts(hits[-1])
    for ev in hits:
        payload = _parse_payload(ev)
        for pid in payload.get("phantom_cards", []) or []:
            if pid not in phantom_ids:
                phantom_ids.append(pid)
    running = _task_field(task, "status") == "running"
    actions: list[DiagnosticAction] = []
    actions.append(DiagnosticAction(
        kind="comment",
        label="Add a comment explaining what to do",
        suggested=False,
    ))
    actions.extend(_generic_recovery_actions(task, running=running))
    return [Diagnostic(
        kind="hallucinated_cards",
        severity="error",
        title="Worker claimed cards that don't exist",
        detail=(
            f"The completing worker declared created_cards that either didn't "
            f"exist or weren't created by its profile. The completion was "
            f"blocked and the task stayed in its prior state. "
            f"Usually means the worker hallucinated ids instead of capturing "
            f"return values from kanban_create."
        ),
        actions=actions,
        first_seen_at=first,
        last_seen_at=last,
        count=len(hits),
        data={"phantom_ids": phantom_ids},
    )]


def _rule_prose_phantom_refs(task, events, runs, now, cfg) -> list[Diagnostic]:
    """Advisory prose-scan: the completion summary mentions ``t_<hex>``
    ids that don't resolve. Non-blocking; surfaced as a warning only.

    Auto-clears when a fresh clean completion arrives AFTER the
    suspected event.
    """
    hits = _active_hallucination_events(events, "suspected_hallucinated_references")
    if not hits:
        return []
    phantom_refs: list[str] = []
    for ev in hits:
        for pid in _parse_payload(ev).get("phantom_refs", []) or []:
            if pid not in phantom_refs:
                phantom_refs.append(pid)
    running = _task_field(task, "status") == "running"
    return [Diagnostic(
        kind="prose_phantom_refs",
        severity="warning",
        title="Completion summary references unknown task ids",
        detail=(
            "The completion summary mentions task ids that don't resolve "
            "in this board's database. The completion itself succeeded, "
            "but downstream consumers parsing the summary may be pointed "
            "at cards that never existed."
        ),
        actions=_generic_recovery_actions(task, running=running),
        first_seen_at=_event_ts(hits[0]),
        last_seen_at=_event_ts(hits[-1]),
        count=len(hits),
        data={"phantom_refs": phantom_refs},
    )]


def _rule_repeated_failures(task, events, runs, now, cfg) -> list[Diagnostic]:
    """Task's unified ``consecutive_failures`` counter is climbing —
    something about this task+profile combo is broken and each retry
    fails the same way. Triggers regardless of the specific failure
    mode (spawn error, timeout, crash) because operationally they
    all look the same: the kernel keeps retrying and the operator
    needs to intervene.

    Threshold: cfg["failure_threshold"] (default 3). A threshold of 3
    is one below the circuit-breaker's default (5), so the diagnostic
    surfaces BEFORE the breaker trips — giving operators a window to
    fix the problem while the dispatcher's still retrying.

    Accepts the legacy ``spawn_failure_threshold`` config key for
    back-compat.
    """
    threshold = int(cfg.get(
        "failure_threshold",
        cfg.get("spawn_failure_threshold", 3),
    ))
    # Read the new unified counter name, with a fallback to the legacy
    # column name so this rule keeps working against old DB rows the
    # caller somehow materialised without running the migration.
    failures = (
        _task_field(task, "consecutive_failures", None)
        if _task_field(task, "consecutive_failures", None) is not None
        else _task_field(task, "spawn_failures", 0)
    )
    if failures is None or failures < threshold:
        return []
    last_err = (
        _task_field(task, "last_failure_error", None)
        if _task_field(task, "last_failure_error", None) is not None
        else _task_field(task, "last_spawn_error", None)
    )
    assignee = _task_field(task, "assignee")

    # Classify the most recent failure by peeking at run outcomes so
    # the title + suggested action can be specific without a separate
    # per-outcome rule.
    ordered_runs = sorted(runs, key=lambda r: _task_field(r, "id", 0))
    most_recent_outcome = None
    for r in reversed(ordered_runs):
        oc = _task_field(r, "outcome")
        if oc in ("spawn_failed", "timed_out", "crashed"):
            most_recent_outcome = oc
            break

    actions: list[DiagnosticAction] = []
    if most_recent_outcome == "spawn_failed" and assignee and assignee != "default":
        # Spawn is failing specifically — profile setup issue.
        actions.append(DiagnosticAction(
            kind="cli_hint",
            label=f"Verify profile: hermes -p {assignee} doctor",
            payload={"command": f"hermes -p {assignee} doctor"},
            suggested=True,
        ))
        actions.append(DiagnosticAction(
            kind="cli_hint",
            label=f"Fix profile auth: hermes -p {assignee} auth",
            payload={"command": f"hermes -p {assignee} auth"},
        ))
    elif most_recent_outcome in ("timed_out", "crashed"):
        # Worker got off the ground but died. Logs are the right place
        # to diagnose; reclaim/reassign are the recovery levers.
        task_id = _task_field(task, "id")
        if task_id:
            actions.append(DiagnosticAction(
                kind="cli_hint",
                label=f"Check logs: hermes kanban log {task_id}",
                payload={"command": f"hermes kanban log {task_id}"},
                suggested=True,
            ))
    actions.extend(_generic_recovery_actions(
        task, running=_task_field(task, "status") == "running",
    ))

    severity = "critical" if failures >= threshold * 2 else "error"
    err_text = (last_err or "").strip() if last_err else ""
    err_snippet = err_text[:500] + ("…" if len(err_text) > 500 else "") if err_text else ""
    outcome_label = {
        "spawn_failed": "spawn",
        "timed_out": "timeout",
        "crashed": "crash",
    }.get(most_recent_outcome or "", "failure")
    if err_snippet:
        title = f"Agent {outcome_label} x{failures}: {err_snippet.splitlines()[0][:160]}"
        detail = (
            f"This task has failed {failures} times in a row "
            f"(most recent: {outcome_label}). Full last error:\n\n"
            f"{err_snippet}\n\n"
            f"The dispatcher will keep retrying until the consecutive-"
            f"failures counter trips the circuit breaker (default 5), "
            f"at which point the task auto-blocks. Fix the root cause "
            f"and reclaim to retry."
        )
    else:
        title = f"Agent {outcome_label} x{failures} (no error recorded)"
        detail = (
            f"This task has failed {failures} times in a row "
            f"(most recent: {outcome_label}) but no error text was "
            f"captured. Check the suggested command or the worker log."
        )
    return [Diagnostic(
        kind="repeated_failures",
        severity=severity,
        title=title,
        detail=detail,
        actions=actions,
        first_seen_at=now,
        last_seen_at=now,
        count=failures,
        data={
            "consecutive_failures": failures,
            "most_recent_outcome": most_recent_outcome,
            "last_error": last_err,
        },
    )]


def _rule_repeated_crashes(task, events, runs, now, cfg) -> list[Diagnostic]:
    """The worker spawns fine but keeps crashing mid-run. Check the last
    N runs' outcomes; N consecutive ``crashed`` without a successful
    ``completed`` means something about the task + profile combo is
    broken (OOM, missing dependency, tool it needs is down).

    Threshold: cfg["crash_threshold"] (default 2).

    Narrower than ``repeated_failures`` — fires earlier (2 crashes vs 3
    total failures) so the operator gets a crash-specific heads-up
    before the unified rule kicks in. Suppresses itself when the
    unified rule is also about to fire, to avoid double-flagging.
    """
    failure_threshold = int(cfg.get(
        "failure_threshold",
        cfg.get("spawn_failure_threshold", 3),
    ))
    unified_counter = (
        _task_field(task, "consecutive_failures", 0) or 0
    )
    # Unified rule will catch this — let it handle to avoid double fire.
    if unified_counter >= failure_threshold:
        return []

    threshold = int(cfg.get("crash_threshold", 2))
    ordered = sorted(runs, key=lambda r: _task_field(r, "id", 0))
    # Count trailing consecutive 'crashed' outcomes.
    consecutive = 0
    last_err = None
    for r in reversed(ordered):
        outcome = _task_field(r, "outcome")
        if outcome == "crashed":
            consecutive += 1
            if last_err is None:
                last_err = _task_field(r, "error")
        elif outcome in ("completed", "reclaimed"):
            # A success (or manual reclaim) breaks the streak.
            break
        else:
            # Other outcomes (timed_out, blocked, spawn_failed, gave_up)
            # aren't crash signals — don't count them, but they also
            # don't break the crash streak.
            continue
    if consecutive < threshold:
        return []
    task_id = _task_field(task, "id")
    actions: list[DiagnosticAction] = []
    if task_id:
        actions.append(DiagnosticAction(
            kind="cli_hint",
            label=f"Check logs: hermes kanban log {task_id}",
            payload={"command": f"hermes kanban log {task_id}"},
            suggested=True,
        ))
    running = _task_field(task, "status") == "running"
    actions.extend(_generic_recovery_actions(task, running=running))
    severity = "critical" if consecutive >= threshold * 2 else "error"
    # Put the actual error up-front so operators see WHAT broke without
    # having to open the logs. Truncate defensively — these can be huge
    # (full tracebacks).
    err_text = (last_err or "").strip() if last_err else ""
    err_snippet = err_text[:500] + ("…" if len(err_text) > 500 else "") if err_text else ""
    if err_snippet:
        title = f"Agent crashed {consecutive}x: {err_snippet.splitlines()[0][:160]}"
        detail = (
            f"The last {consecutive} runs ended with outcome=crashed. "
            f"Full last error:\n\n{err_snippet}"
        )
    else:
        title = f"Agent crashed {consecutive}x (no error recorded)"
        detail = (
            f"The last {consecutive} runs ended with outcome=crashed but "
            f"no error text was captured. Check the worker log for more."
        )
    return [Diagnostic(
        kind="repeated_crashes",
        severity=severity,
        title=title,
        detail=detail,
        actions=actions,
        first_seen_at=now,
        last_seen_at=now,
        count=consecutive,
        data={"consecutive_crashes": consecutive, "last_error": last_err},
    )]


def _rule_stuck_in_blocked(task, events, runs, now, cfg) -> list[Diagnostic]:
    """Task has been in ``blocked`` status for too long without a comment.

    Threshold: cfg["blocked_stale_hours"] (default 24).
    Surfaced as a warning so humans know there's a pending unblock.
    """
    hours = float(cfg.get("blocked_stale_hours", 24))
    status = _task_field(task, "status")
    if status != "blocked":
        return []
    # Find the most recent ``blocked`` event.
    last_blocked_ts = 0
    for ev in events:
        if _event_kind(ev) == "blocked":
            t = _event_ts(ev)
            if t > last_blocked_ts:
                last_blocked_ts = t
    if last_blocked_ts == 0:
        return []
    age_hours = (now - last_blocked_ts) / 3600.0
    if age_hours < hours:
        return []
    # Any comment / unblock after the block breaks the "stale" signal.
    for ev in events:
        if _event_kind(ev) in ("commented", "unblocked") and _event_ts(ev) > last_blocked_ts:
            return []
    actions: list[DiagnosticAction] = [
        DiagnosticAction(
            kind="comment",
            label="Add a comment / unblock the task",
            suggested=True,
        ),
    ]
    return [Diagnostic(
        kind="stuck_in_blocked",
        severity="warning",
        title=f"Task has been blocked for {int(age_hours)}h",
        detail=(
            f"This task transitioned to blocked {int(age_hours)}h ago and "
            f"has had no comments or unblock attempts since. Blocked tasks "
            f"are waiting for human input — check the block reason and "
            f"either unblock with feedback or answer with a comment."
        ),
        actions=actions,
        first_seen_at=last_blocked_ts,
        last_seen_at=last_blocked_ts,
        count=1,
        data={"blocked_at": last_blocked_ts, "age_hours": round(age_hours, 1)},
    )]


# Registry — order matters: rules higher on the list render first when
# severity ties. Add new rules here.
_RULES: list[RuleFn] = [
    _rule_hallucinated_cards,
    _rule_prose_phantom_refs,
    _rule_repeated_failures,
    _rule_repeated_crashes,
    _rule_stuck_in_blocked,
]


# Known kinds (for the UI's filter / legend / i18n keys). Update when
# rules are added.
DIAGNOSTIC_KINDS = (
    "hallucinated_cards",
    "prose_phantom_refs",
    "repeated_failures",
    "repeated_crashes",
    "stuck_in_blocked",
)


DEFAULT_CONFIG = {
    "failure_threshold": 3,
    # Legacy alias accepted at read time by _rule_repeated_failures.
    "spawn_failure_threshold": 3,
    "crash_threshold": 2,
    "blocked_stale_hours": 24,
}


def compute_task_diagnostics(
    task,
    events: list,
    runs: list,
    *,
    now: Optional[int] = None,
    config: Optional[dict] = None,
) -> list[Diagnostic]:
    """Run every rule against a single task's state and return a
    severity-sorted list of active diagnostics.

    Sorting: critical first, then error, then warning; ties broken by
    most-recent ``last_seen_at``.
    """
    now_ts = int(now if now is not None else time.time())
    cfg = {**DEFAULT_CONFIG, **(config or {})}
    out: list[Diagnostic] = []
    for rule in _RULES:
        try:
            out.extend(rule(task, events, runs, now_ts, cfg))
        except Exception:
            # A broken rule must never crash the dashboard. Rule bugs
            # get caught in tests; in production we'd rather drop the
            # diagnostic than 500 a whole /board request.
            continue
    severity_idx = {s: i for i, s in enumerate(SEVERITY_ORDER)}
    out.sort(
        key=lambda d: (
            -severity_idx.get(d.severity, -1),
            -(d.last_seen_at or 0),
        )
    )
    return out


def severity_of_highest(diagnostics: Iterable[Diagnostic]) -> Optional[str]:
    """Highest severity present in the list, or None if empty. Useful
    for card badges that need a single color."""
    highest_idx = -1
    highest = None
    for d in diagnostics:
        idx = SEVERITY_ORDER.index(d.severity) if d.severity in SEVERITY_ORDER else -1
        if idx > highest_idx:
            highest_idx = idx
            highest = d.severity
    return highest