from __future__ import annotations

from collections.abc import Mapping, Sequence
from datetime import datetime
from urllib.parse import urlencode

from ..security import admin_csrf_token
from ..services.ddns import DdnsService
from ..settings import DdnsSettings
from .html_utils import SafeHtml, attr, escape, trusted
from .layout import _page, _top_nav
from .templates_admin_tables import (
    _account_row,
    _admin_table_pagination,
    _admin_table_toolbar,
    _event_row,
)


def _admin_secret_panel(title: str, rows: list[SafeHtml]) -> SafeHtml:
    return trusted(f"""
    <section class="section success-section">
      <div class="container">
        <p class="eyebrow">Admin action</p>
        <h2>{escape(title)}</h2>
        <p class="section-copy">Copy these values now. Secret values are only shown once.</p>
        <div class="d-grid gap-2">
          {"".join(rows)}
        </div>
      </div>
    </section>
    """)


def _render_admin_page(
    service: DdnsService,
    settings: DdnsSettings,
    accounts: Sequence[Mapping[str, object]],
    cleanup_runs: Sequence[Mapping[str, object]],
    scheduled_tasks: Sequence[Mapping[str, object]],
    update_events: Sequence[Mapping[str, object]],
    service_metrics: dict[str, float],
    table_counts: dict[str, int],
    table_offsets: dict[str, int],
    table_limit: int,
    notice_html: SafeHtml | None,
) -> str:
    csrf = attr(admin_csrf_token(settings))
    admin_path = settings.admin_path
    safe_admin_path = attr(admin_path)
    rows = "\n".join(_account_row(account, csrf=csrf, admin_path=admin_path) for account in accounts) or """
      <tr class="empty-row"><td colspan="7" class="empty">No hostnames yet.</td></tr>
    """
    event_rows = "\n".join(_event_row(event) for event in update_events) or """
      <tr class="empty-row"><td colspan="7" class="empty">No update events yet.</td></tr>
    """
    accounts_count = escape(table_counts.get("accounts", len(accounts)))
    event_count = escape(table_counts.get("update_events", len(update_events)))
    metrics_html = _metrics_panel(service_metrics)
    account_pager = _server_page_links(
        admin_path, "accounts_offset", table_offsets.get("accounts", 0), table_limit, table_counts.get("accounts", 0)
    )
    event_pager = _server_page_links(
        admin_path,
        "update_events_offset",
        table_offsets.get("update_events", 0),
        table_limit,
        table_counts.get("update_events", 0),
    )
    cleanup_panel = _cleanup_panel(settings, cleanup_runs, scheduled_tasks, safe_admin_path, csrf)
    totals_html = _totals_strip(table_counts, service_metrics)
    return _page(
        "KarlDNS Admin",
        trusted(f"""
        <main id="main">
          {_top_nav("Operator")}
          <section class="admin-console">
            <div class="container">
              <div class="admin-page-title">
                <div>
                  <p class="eyebrow">KarlDNS</p>
                  <h1>Operator console</h1>
                </div>
                {totals_html}
              </div>
            </div>
          </section>

          {notice_html or ""}

          <section class="admin-block">
            <div class="container">
              {cleanup_panel}
              {metrics_html}
            </div>
          </section>

          <section class="admin-block">
            <div class="container">
              <div class="admin-section-heading">
                <div>
                  <h2>Hostnames</h2>
                  <p class="section-copy mb-0">{escape(len(accounts))} of {accounts_count} shown.</p>
                </div>
              </div>
              {_admin_table_toolbar("hostnames", "Search hostnames")}
              <div class="table-responsive border rounded admin-table-scroll">
                <table class="table mb-0">
                  <thead>
                    <tr><th scope="col">Hostname</th><th scope="col">Status</th><th scope="col">IPv4</th><th scope="col">IPv6</th><th scope="col">Updated</th><th scope="col">Links</th><th scope="col">Actions</th></tr>
                  </thead>
                  <tbody>{rows}</tbody>
                </table>
              </div>
              {_admin_table_pagination()}
              {account_pager}
            </div>
          </section>

          <section class="admin-block">
            <div class="container">
              <div class="admin-section-heading">
                <div>
                  <h2>Update events</h2>
                  <p class="section-copy mb-0">{escape(len(update_events))} of {event_count} shown. Unchanged checks are grouped.</p>
                </div>
              </div>
              {_admin_table_toolbar("update-events", "Search update events")}
              <div class="table-responsive border rounded admin-table-scroll">
                <table class="table mb-0">
                  <thead><tr><th scope="col">Time</th><th scope="col">Hostname</th><th scope="col">Status</th><th scope="col">IPv4</th><th scope="col">IPv6</th><th scope="col">Count</th><th scope="col">Detail</th></tr></thead>
                  <tbody>{event_rows}</tbody>
                </table>
              </div>
              {_admin_table_pagination()}
              {event_pager}
            </div>
          </section>
        </main>
        """),
        extra_styles=trusted('<link href="/admin.css?v=5" rel="stylesheet">'),
        extra_scripts=trusted('<script src="/admin-tables.js?v=2" defer></script>'),
    )


def _totals_strip(table_counts: dict[str, int], metrics: dict[str, float]) -> SafeHtml:
    items = [
        ("Hostnames", table_counts.get("accounts", 0)),
        ("Events", table_counts.get("update_events", 0)),
        ("DNS failures", int(metrics.get("dns_failures_total", 0))),
        ("Blocked", int(metrics.get("rate_limit_hits_total", 0))),
    ]
    return trusted(
        '<div class="admin-total-strip" aria-label="Service totals">'
        + "".join(f"<span><strong>{escape(value)}</strong>{escape(label)}</span>" for label, value in items)
        + "</div>"
    )


def _admin_notice(kind: str, message: str) -> SafeHtml:
    alert_class = "alert-success" if kind == "success" else "alert-info"
    return trusted(f"""
      <div class="container">
        <div class="alert {alert_class} admin-notice" role="status">{escape(message)}</div>
      </div>
    """)


def _server_page_links(admin_path: str, offset_name: str, offset: int, limit: int, total: int) -> SafeHtml:
    if total <= limit:
        return trusted("")
    previous_offset = max(0, offset - limit)
    next_offset = offset + limit
    previous_disabled = " disabled" if offset <= 0 else ""
    next_disabled = " disabled" if next_offset >= total else ""
    previous_href = attr(f"{admin_path}?{urlencode({offset_name: previous_offset})}")
    next_href = attr(f"{admin_path}?{urlencode({offset_name: next_offset})}")
    start = min(offset + 1, total)
    end = min(offset + limit, total)
    return trusted(f"""
      <nav class="d-flex align-items-center justify-content-end gap-2 mt-2" aria-label="Server-side table pages">
        <span class="small text-secondary">{escape(start)}-{escape(end)} of {escape(total)}</span>
        <a class="btn btn-sm btn-light rounded-pill{previous_disabled}" href="{previous_href}" aria-disabled="{str(offset <= 0).lower()}">Previous</a>
        <a class="btn btn-sm btn-light rounded-pill{next_disabled}" href="{next_href}" aria-disabled="{str(next_offset >= total).lower()}">Next</a>
      </nav>
    """)


def _cleanup_panel(
    settings: DdnsSettings,
    cleanup_runs: Sequence[Mapping[str, object]],
    scheduled_tasks: Sequence[Mapping[str, object]],
    safe_admin_path: str,
    csrf: str,
) -> SafeHtml:
    task = next(
        (item for item in scheduled_tasks if item.get("name") == "cleanup"),
        scheduled_tasks[0] if scheduled_tasks else {},
    )
    last_run = task.get("last_finished_at") or (cleanup_runs[0].get("created_at") if cleanup_runs else None)
    next_run = task.get("next_run_at")
    status = task.get("last_status") or "pending"
    last_error = task.get("last_error") or ""
    interval = task.get("interval_seconds") or settings.cleanup_interval_seconds
    last_cleanup = cleanup_runs[0] if cleanup_runs else {}
    accounts_removed = last_cleanup.get("unused_accounts_deleted", 0)
    error_html = (
        trusted(f'<p class="small text-danger mb-0">Last error: {escape(last_error)}</p>')
        if last_error
        else trusted("")
    )
    last_run_title = attr(str(last_run or "Never"))
    next_run_title = attr(str(next_run or "Pending"))
    last_run_display = escape(_format_timestamp(last_run, "Never"))
    next_run_display = escape(_format_timestamp(next_run, "Pending"))
    return trusted(f"""
      <div class="admin-cleanup-bar">
        <div class="admin-cleanup-title">
          <h2>Cleanup</h2>
          <span>Every {escape(_format_interval(interval))}</span>
        </div>
        <dl class="admin-cleanup-times">
          <div><dt>Last run</dt><dd title="{last_run_title}">{last_run_display}</dd></div>
          <div><dt>Next run</dt><dd title="{next_run_title}">{next_run_display}</dd></div>
          <div><dt>Status</dt><dd>{escape(str(status))}</dd></div>
          <div><dt>Removed</dt><dd>{escape(accounts_removed)}</dd></div>
        </dl>
        {error_html}
        <form method="post" action="{safe_admin_path}/cleanup" aria-label="Run cleanup now">
          <input type="hidden" name="csrf" value="{csrf}">
          <button type="submit" class="btn btn-primary rounded-pill">Run now</button>
        </form>
      </div>
    """)


def _metrics_panel(metrics: dict[str, float]) -> SafeHtml:
    samples = metrics.get("update_latency_samples_total", 0)
    average_latency = metrics.get("update_latency_ms_total", 0) / samples if samples else 0
    items = [
        ("Updates", _metric_int(metrics.get("update_requests_total", 0))),
        ("Updated", _metric_int(metrics.get("update_success_total", 0))),
        ("DNS failures", _metric_int(metrics.get("dns_failures_total", 0))),
        ("DNS check failures", _metric_int(metrics.get("dns_reconcile_failures_total", 0))),
        ("Blocked requests", _metric_int(metrics.get("rate_limit_hits_total", 0))),
        ("Average update time", f"{average_latency:.1f} ms"),
        ("Last update time", f"{metrics.get('last_update_latency_ms', 0):.1f} ms"),
        (
            "Cleanup ok/errors",
            f"{_metric_int(metrics.get('cleanup_success_total', 0))}/{_metric_int(metrics.get('cleanup_errors_total', 0))}",
        ),
    ]
    cards = "\n".join(f"""
        <span><strong>{escape(value)}</strong>{escape(label)}</span>
        """ for label, value in items)
    return trusted(f"""
      <div class="admin-metric-strip" aria-label="Service metrics">
        {cards}
      </div>
    """)


def _metric_int(value: object) -> str:
    try:
        return str(int(float(str(value))))
    except ValueError:
        return "0"


def _format_interval(seconds: object) -> str:
    try:
        value = int(str(seconds))
    except (TypeError, ValueError):
        return str(seconds)
    if value % 3600 == 0:
        hours = value // 3600
        return f"{hours}h"
    if value % 60 == 0:
        minutes = value // 60
        return f"{minutes}m"
    return f"{value}s"


def _format_timestamp(value: object, fallback: str = "-") -> str:
    if not value:
        return fallback
    raw = str(value)
    try:
        parsed = datetime.fromisoformat(raw)
    except ValueError:
        return raw
    return parsed.strftime("%Y-%m-%d %H:%M")