from __future__ import annotations
from datetime import datetime, timezone
from quart import Blueprint, render_template, request, redirect, url_for, current_app, session
from steward.core.audit import log_audit
from sqlalchemy import select
from steward.auth.middleware import require_role
from steward.alerts import service as alert_svc
from steward.core.time_range import parse_range
from steward.ansible import sources as src_module
from steward.models.alerts import AlertRule, AlertOperator, MaintenanceWindow
from steward.models.users import UserRole

alerts_bp = Blueprint("alerts", __name__, url_prefix="/alerts")

_OPERATORS = [(op.value, op.value) for op in AlertOperator]

def _rule_form(form) -> dict:
    """The rule form's fields, as alert_svc.rule_fields takes them."""
    return {
        "name": form.get("name", ""),
        "source_module": form.get("source_module", ""),
        "resource_name": form.get("resource_name", ""),
        "metric_name": form.get("metric_name", ""),
        "operator": form.get("operator", ""),
        "threshold": form.get("threshold"),
        "consecutive_failures_required": form.get("consecutive_failures_required"),
        "consecutive_ok_required": form.get("consecutive_ok_required"),
        "notify_no_data": "notify_no_data" in form,
    }


def _form_time(value) -> datetime:
    """A datetime-local field, read as UTC."""
    try:
        return datetime.fromisoformat((value or "").strip()).replace(tzinfo=timezone.utc)
    except ValueError:
        raise ValueError(f"{value!r} is not a date and time.") from None


def _is_admin() -> bool:
    return session.get("user_role") == UserRole.admin.value


def _ansible_source_names() -> list[str]:
    try:
        return [s["name"] for s in src_module.get_sources(current_app.config.get("ANSIBLE", {}))]
    except Exception:
        return []


def _parse_ansible_action(form) -> tuple[dict | None, str | None]:
    """Parse + validate the admin-only Ansible action from a rule form.

    Returns (action_or_None, error_or_None). action is None when the action
    checkbox is unchecked (i.e. the action is being cleared).
    """
    if "ansible_enabled" not in form:
        return None, None
    source_name = (form.get("ansible_source", "") or "").strip()
    playbook = (form.get("ansible_playbook", "") or "").strip()
    inventory = (form.get("ansible_inventory", "") or "").strip()
    if not (source_name and playbook and inventory):
        return None, "Ansible action requires source, playbook, and inventory"
    try:
        srcs = src_module.get_sources(current_app.config.get("ANSIBLE", {}))
    except Exception:
        return None, "Ansible sources are misconfigured"
    source = next((s for s in srcs if s["name"] == source_name), None)
    if source is None:
        return None, f"Ansible source '{source_name}' not found"
    if playbook not in src_module.discover_playbooks(source["path"]):
        return None, f"Playbook '{playbook}' not found in source '{source_name}'"
    extra_vars: list[str] = []
    for line in (form.get("ansible_extra_vars", "") or "").splitlines():
        line = line.strip()
        if not line:
            continue
        if "=" not in line:
            return None, f"Invalid extra var (expected key=value): {line!r}"
        extra_vars.append(line)
    action: dict = {"source": source_name, "playbook": playbook, "inventory": inventory}
    if extra_vars:
        action["extra_vars"] = extra_vars
    limit = (form.get("ansible_limit", "") or "").strip()
    tags = (form.get("ansible_tags", "") or "").strip()
    if limit:
        action["limit"] = limit
    if tags:
        action["tags"] = tags
    if "ansible_check" in form:
        action["check"] = True
    return action, None


@alerts_bp.get("/")
@require_role(UserRole.viewer)
async def list_alerts():
    async with current_app.db_sessionmaker() as db:
        active = await alert_svc.active_rows(db, datetime.now(timezone.utc))
        rules = await alert_svc.list_rules(db)

    return await render_template("alerts/list.html", active=active, rules=rules, operators=_OPERATORS)


HISTORY_LIMIT = 200


def _history_row(event, rule) -> dict:
    """One transition as the history page shows it."""
    from steward.core.alerts import MUTED, RELEASED
    notes, muted_by, released = [], None, False
    for part in (event.note or "").split("; "):
        if part.startswith(MUTED):
            muted_by = part[len(MUTED):].strip() or "a maintenance window"
        elif part == RELEASED:
            released = True
        elif part:
            notes.append(part)
    value = "no data" if event.metric_value is None else f"{event.metric_value:g}"
    return {
        "at": event.transitioned_at, "rule": rule,
        "from_state": event.from_state, "to_state": event.to_state,
        "value": value, "condition": f"{rule.operator.value} {rule.threshold:g}",
        "notes": notes, "muted_by": muted_by, "released": released,
        "deliveries": [(label, sent, error) for label, sent, error in (
            ("email", event.email_sent, event.email_error),
            ("webhook", event.webhook_sent, event.webhook_error)) if sent is not None],
        "ansible_run_id": event.ansible_run_id,
    }


@alerts_bp.get("/history")
@require_role(UserRole.viewer)
async def alert_history():
    """Every alert transition in a range, newest first; one rule's with ?rule=."""
    since, range_key = parse_range(request.args.get("range") or "7d")
    async with current_app.db_sessionmaker() as db:
        rules = await alert_svc.list_rules(db)
        chosen = next((r for r in rules if r.id == request.args.get("rule")), None)
        rows = await alert_svc.history(db, since, chosen.id if chosen else None, HISTORY_LIMIT)
    ctx = {"events": [_history_row(e, r) for e, r in rows[:HISTORY_LIMIT]],
           "truncated": len(rows) > HISTORY_LIMIT, "limit": HISTORY_LIMIT,
           "rules": rules, "chosen": chosen, "current_range": range_key}
    if request.headers.get("HX-Request"):
        return await render_template("alerts/_history_rows.html", **ctx)
    return await render_template("alerts/history.html", **ctx)


@alerts_bp.get("/api/rule_fields")
@require_role(UserRole.viewer)
async def rule_fields_api():
    source = request.args.get("source_module", "")
    current_resource = request.args.get("current_resource", "")
    current_metric = request.args.get("current_metric", "")
    async with current_app.db_sessionmaker() as db:
        resources = await alert_svc.resources_for(db, source) if source else []
    async with current_app.db_sessionmaker() as db:
        metrics = await alert_svc.metrics_for(db, source)
    return await render_template(
        "alerts/_rule_fields.html",
        resources=resources,
        metrics=metrics,
        current_resource=current_resource,
        current_metric=current_metric,
    )


@alerts_bp.get("/rules/new")
@require_role(UserRole.operator)
async def new_rule():
    first_source = alert_svc.source_modules()[0]
    async with current_app.db_sessionmaker() as db:
        resources = await alert_svc.resources_for(db, first_source)
    return await render_template(
        "alerts/rules_form.html",
        rule=None,
        operators=_OPERATORS,
        source_modules=alert_svc.source_modules(),
        initial_source=first_source,
        resources=resources,
        metrics=alert_svc.metric_catalog().get(first_source, []),
        ansible_sources=_ansible_source_names(),
    )


@alerts_bp.get("/rules/<rule_id>/edit")
@require_role(UserRole.operator)
async def edit_rule(rule_id: str):
    async with current_app.db_sessionmaker() as db:
        result = await db.execute(select(AlertRule).where(AlertRule.id == rule_id))
        rule = result.scalar_one_or_none()
        if rule is None:
            return "Not found", 404
        resources = await alert_svc.resources_for(db, rule.source_module)
    return await render_template(
        "alerts/rules_form.html",
        rule=rule,
        operators=_OPERATORS,
        source_modules=alert_svc.source_modules(),
        initial_source=rule.source_module,
        resources=resources,
        metrics=alert_svc.metric_catalog().get(rule.source_module, []),
        ansible_sources=_ansible_source_names(),
    )


@alerts_bp.post("/rules")
@require_role(UserRole.operator)
async def create_rule():
    form = await request.form
    user_id = session.get("user_id")
    # Ansible action is admin-only; non-admins simply can't set one.
    ansible_action = None
    if _is_admin():
        ansible_action, err = _parse_ansible_action(form)
        if err:
            return err, 400
    async with current_app.db_sessionmaker() as db:
        async with db.begin():
            try:
                fields = await alert_svc.rule_fields(db, **_rule_form(form))
            except ValueError as exc:
                return str(exc), 400
            rule = await alert_svc.add_rule(db, fields, created_by=user_id,
                                            ansible_action=ansible_action)
    await log_audit(current_app, user_id, session.get("username", ""), "alert_rule.created",
                    entity_type="alert_rule", entity_id=rule.name,
                    detail={"source": rule.source_module, "resource": rule.resource_name,
                            "metric": rule.metric_name})
    return redirect(url_for("alerts.list_alerts"))


@alerts_bp.post("/rules/<rule_id>")
@require_role(UserRole.operator)
async def update_rule(rule_id: str):
    form = await request.form
    # Validate the admin-only action before opening the transaction. Non-admins
    # leave the existing action untouched (they can still edit everything else).
    apply_action = _is_admin()
    if apply_action:
        ansible_action, err = _parse_ansible_action(form)
        if err:
            return err, 400
    async with current_app.db_sessionmaker() as db:
        async with db.begin():
            result = await db.execute(select(AlertRule).where(AlertRule.id == rule_id))
            rule = result.scalar_one_or_none()
            if rule is None:
                return "Not found", 404
            try:
                fields = await alert_svc.rule_fields(db, **_rule_form(form))
            except ValueError as exc:
                return str(exc), 400
            await alert_svc.apply_rule_change(db, rule, fields)
            if apply_action:
                rule.ansible_action = ansible_action
    await log_audit(current_app, session.get("user_id"), session.get("username", ""),
                    "alert_rule.updated", entity_type="alert_rule", entity_id=rule.name)
    return redirect(url_for("alerts.list_alerts"))


@alerts_bp.post("/rules/<rule_id>/toggle")
@require_role(UserRole.operator)
async def toggle_rule(rule_id: str):
    async with current_app.db_sessionmaker() as db:
        async with db.begin():
            result = await db.execute(select(AlertRule).where(AlertRule.id == rule_id))
            rule = result.scalar_one_or_none()
            if rule is None:
                return "Not found", 404
            await alert_svc.apply_rule_change(db, rule, {}, enabled=not rule.enabled)
    action = "alert_rule.enabled" if rule.enabled else "alert_rule.disabled"
    await log_audit(current_app, session.get("user_id"), session.get("username", ""),
                    action, entity_type="alert_rule", entity_id=rule.name)
    return redirect(url_for("alerts.list_alerts"))


@alerts_bp.post("/rules/<rule_id>/delete")
@require_role(UserRole.admin)
async def delete_rule(rule_id: str):
    rule_name = None
    async with current_app.db_sessionmaker() as db:
        async with db.begin():
            result = await db.execute(select(AlertRule).where(AlertRule.id == rule_id))
            rule = result.scalar_one_or_none()
            if rule:
                rule_name = rule.name
                await db.delete(rule)
    if rule_name:
        await log_audit(current_app, session.get("user_id"), session.get("username", ""),
                        "alert_rule.deleted", entity_type="alert_rule", entity_id=rule_name)
    return redirect(url_for("alerts.list_alerts"))


@alerts_bp.get("/maintenance")
@require_role(UserRole.viewer)
async def list_maintenance():
    now = datetime.now(timezone.utc)
    async with current_app.db_sessionmaker() as db:
        windows = await alert_svc.list_maintenance_windows(db)
    return await render_template(
        "alerts/maintenance.html",
        windows=windows,
        now=now,
        source_modules=alert_svc.source_modules(),
    )


@alerts_bp.get("/maintenance/new")
@require_role(UserRole.operator)
async def new_maintenance():
    return await render_template(
        "alerts/maintenance_form.html",
        window=None,
        source_modules=alert_svc.source_modules(),
    )


@alerts_bp.post("/maintenance")
@require_role(UserRole.operator)
async def create_maintenance():
    form = await request.form
    user_id = session.get("user_id")
    try:
        fields = alert_svc.window_fields(
            name=form.get("name", ""),
            start_at=_form_time(form.get("start_at")), end_at=_form_time(form.get("end_at")),
            scope_source=form.get("scope_source"), scope_resource=form.get("scope_resource"))
    except ValueError as exc:
        return str(exc), 400
    window = MaintenanceWindow(created_by=user_id, **fields)
    async with current_app.db_sessionmaker() as db:
        async with db.begin():
            db.add(window)
    scope_desc = alert_svc.window_scope(window)
    await log_audit(current_app, user_id, session.get("username", ""),
                    "maintenance_window.created", entity_type="maintenance_window",
                    entity_id=window.name, detail={"scope": scope_desc})
    return redirect(url_for("alerts.list_maintenance"))


@alerts_bp.post("/maintenance/<window_id>/delete")
@require_role(UserRole.operator)
async def delete_maintenance(window_id: str):
    window_name = None
    async with current_app.db_sessionmaker() as db:
        async with db.begin():
            result = await db.execute(
                select(MaintenanceWindow).where(MaintenanceWindow.id == window_id)
            )
            window = result.scalar_one_or_none()
            if window:
                window_name = window.name
                await db.delete(window)
    if window_name:
        await log_audit(current_app, session.get("user_id"), session.get("username", ""),
                        "maintenance_window.deleted", entity_type="maintenance_window",
                        entity_id=window_name)
    return redirect(url_for("alerts.list_maintenance"))


@alerts_bp.post("/<rule_id>/acknowledge")
@require_role(UserRole.operator)
async def acknowledge(rule_id: str):
    user_id = session.get("user_id")
    async with current_app.db_sessionmaker() as db:
        async with db.begin():
            try:
                await alert_svc.acknowledge(db, rule_id, user_id)
            except LookupError:
                return "Not found", 404
            except ValueError as exc:
                return f"Conflict: {exc}", 409
    return redirect(url_for("alerts.list_alerts"))