"""Diagnostics support for the Maintenance Supporter integration."""

from __future__ import annotations

from collections.abc import Mapping
from typing import TYPE_CHECKING, Any

from homeassistant.components.diagnostics import async_redact_data
from homeassistant.core import HomeAssistant

from .const import (
    CONF_OBJECT,
    CONF_TASKS,
    DOMAIN,
    GLOBAL_UNIQUE_ID,
    MaintenanceStatus,
    TriggerEntityState,
)
from .helpers.schedule import read_legacy_fields

if TYPE_CHECKING:
    from . import MaintenanceSupporterConfigEntry

# Fields to redact from diagnostics (downloads are admin-accessible and routinely
# pasted into public GitHub issues, so anything free-text / identifying is redacted)
TO_REDACT = {
    "checklist",
    "notes",
    "documentation_url",
    "manufacturer",
    "model",
    "name",
    "nfc_tag_id",
    "notify_service",
    "responsible_user_id",
    "serial_number",
}


async def async_get_config_entry_diagnostics(hass: HomeAssistant, entry: MaintenanceSupporterConfigEntry) -> dict[str, Any]:
    """Return diagnostics for a config entry."""
    is_global = entry.unique_id == GLOBAL_UNIQUE_ID

    diag: dict[str, Any] = {
        "entry": {
            "title": entry.title,
            "unique_id": entry.unique_id,
            "version": entry.version,
            "is_global": is_global,
        },
        "data": async_redact_data(entry.data, TO_REDACT),
    }

    if is_global:
        # Global entry diagnostics
        diag["options"] = async_redact_data(entry.options or {}, TO_REDACT)
        diag["overview"] = _get_integration_overview(hass)
    else:
        # Object entry diagnostics — merge Store dynamic data for stats
        runtime_data = getattr(entry, "runtime_data", None)
        store = getattr(runtime_data, "store", None) if runtime_data else None
        static_tasks = entry.data.get(CONF_TASKS, {})
        merged_tasks = store.merge_all_tasks(static_tasks) if store is not None else static_tasks
        merged_data = dict(entry.data)
        merged_data[CONF_TASKS] = merged_tasks

        diag["statistics"] = _calculate_statistics(merged_data)
        diag["trigger_status"] = _check_trigger_status(hass, entry.data)
        diag["data_quality"] = _check_data_quality(entry.data)

        # Coordinator info
        runtime_data = getattr(entry, "runtime_data", None)
        if runtime_data and runtime_data.coordinator:
            coord = runtime_data.coordinator
            diag["coordinator"] = {
                "last_update_success": coord.last_update_success,
                "last_update_success_time": str(getattr(coord, "last_update_success_time", None)),
                "update_interval": str(coord.update_interval),
            }

    return diag


def _get_integration_overview(hass: HomeAssistant) -> dict[str, Any]:
    """Get an overview of all maintenance objects."""
    entries = hass.config_entries.async_entries(DOMAIN)
    objects = [e for e in entries if e.unique_id != GLOBAL_UNIQUE_ID]

    total_tasks = 0
    overdue = 0
    due_soon = 0

    for entry in objects:
        tasks = entry.data.get(CONF_TASKS, {})
        total_tasks += len(tasks)

        runtime_data = getattr(entry, "runtime_data", None)
        if runtime_data and runtime_data.coordinator and runtime_data.coordinator.data:
            for task_data in runtime_data.coordinator.data.get("tasks", {}).values():
                status = task_data.get("_status")
                if status == MaintenanceStatus.OVERDUE:
                    overdue += 1
                elif status == MaintenanceStatus.DUE_SOON:
                    due_soon += 1

    return {
        "total_objects": len(objects),
        "total_tasks": total_tasks,
        "overdue_tasks": overdue,
        "due_soon_tasks": due_soon,
    }


def _calculate_statistics(data: Mapping[str, Any]) -> dict[str, Any]:
    """Calculate statistics for a maintenance object."""
    tasks = data.get(CONF_TASKS, {})

    stats: dict[str, Any] = {
        "total_tasks": len(tasks),
        "enabled_tasks": sum(1 for t in tasks.values() if t.get("enabled", True)),
        "tasks_with_triggers": sum(1 for t in tasks.values() if t.get("trigger_config")),
        "tasks_by_type": {},
        "tasks_by_schedule": {},
        "total_history_entries": 0,
    }

    for task in tasks.values():
        # By type
        task_type = task.get("type", "unknown")
        stats["tasks_by_type"][task_type] = stats["tasks_by_type"].get(task_type, 0) + 1

        # By schedule (accepts flat v2.6.x or nested `schedule` storage)
        schedule = read_legacy_fields(task)["schedule_type"]
        stats["tasks_by_schedule"][schedule] = stats["tasks_by_schedule"].get(schedule, 0) + 1

        # History
        stats["total_history_entries"] += len(task.get("history", []))

    return stats


def _check_trigger_status(hass: HomeAssistant, data: Mapping[str, Any]) -> list[dict[str, Any]]:
    """Check the status of all configured triggers."""
    results = []
    tasks = data.get(CONF_TASKS, {})

    for task_id, task in tasks.items():
        trigger_config = task.get("trigger_config")
        if not trigger_config:
            continue

        entity_ids: list[str] = list(trigger_config.get("entity_ids", []))
        if not entity_ids:
            single = trigger_config.get("entity_id")
            if single:
                entity_ids = [single]
        # Compound triggers: collect entity_ids from conditions
        if not entity_ids and trigger_config.get("type") == "compound":
            for cond in trigger_config.get("conditions", []):
                for eid in cond.get("entity_ids", []):
                    if eid not in entity_ids:
                        entity_ids.append(eid)
                cond_eid = cond.get("entity_id")
                if cond_eid and cond_eid not in entity_ids:
                    entity_ids.append(cond_eid)
        if not entity_ids:
            continue

        for eid in entity_ids:
            state = hass.states.get(eid)

            if state is None:
                entity_health = TriggerEntityState.MISSING
            elif state.state in ("unavailable", "unknown"):
                entity_health = TriggerEntityState.UNAVAILABLE
            else:
                entity_health = TriggerEntityState.AVAILABLE

            results.append(
                {
                    "task_id": task_id,
                    "trigger_entity": eid,
                    "trigger_type": trigger_config.get("type"),
                    "entity_available": state is not None,
                    # raw entity_state intentionally omitted — it can carry PII
                    # (e.g. a device_tracker / person location); entity_health
                    # gives the available/unavailable/missing status for debugging.
                    "entity_health": entity_health,
                }
            )

    return results


def _check_data_quality(data: Mapping[str, Any]) -> list[str]:
    """Check data quality and return warnings."""
    warnings = []

    obj = data.get(CONF_OBJECT, {})
    tasks = data.get(CONF_TASKS, {})

    if not obj.get("name"):
        warnings.append("Object has no name")

    if not tasks:
        warnings.append("Object has no tasks defined")

    for task_id, task in tasks.items():
        if not task.get("name"):
            warnings.append(f"Task {task_id} has no name")

        sched = read_legacy_fields(task)
        if sched["schedule_type"] == "time_based" and not sched["interval_days"]:
            warnings.append(f"Task '{task.get('name', task_id)}' is time-based but has no interval")

        trigger = task.get("trigger_config")
        if trigger and trigger.get("type") != "compound" and not trigger.get("entity_id"):
            warnings.append(f"Task '{task.get('name', task_id)}' has trigger config but no entity")

    return warnings