import {useMemo, useState} from 'react'
import {Activity, RefreshCw} from 'lucide-react'
import {Link, Navigate, useParams} from 'react-router-dom'
import {useCloudDiagnosticsQuery} from '@/api/queries/cloudQueries'
import {formatDateTime, formatRelativeTime} from '@/lib/format'
import type {CloudProvider, CloudServiceStatus, EmulatedServiceStatus, RuntimeDiagnostics} from '@/types/cloud'

type ServiceFilter = 'all' | 'not-running' | 'with-page' | 'without-page'

const SERVICE_FILTERS: Array<{id: ServiceFilter; label: string}> = [
    {id: 'all', label: 'All'},
    {id: 'not-running', label: 'Not running'},
    {id: 'with-page', label: 'Has console page'},
    {id: 'without-page', label: 'No console page'},
]

export function DiagnosticsPage() {
    const params = useParams()
    const cloud = normalizeCloud(params.cloud)
    const query = useCloudDiagnosticsQuery(cloud ?? 'aws')

    if (!cloud) return <Navigate to="/diagnostics/aws" replace/>

    const report = query.data
    return (
        <>
            <div className="page-header cloud-explorer-header">
                <div className="page-title">
                    <Activity size={20}/>
                    <div>
                        <h1>Diagnostics</h1>
                        <p className="muted">{report ? `Checked ${formatRelativeTime(report.checkedAt) ?? 'just now'}` : 'Runtime, services and console health'}</p>
                    </div>
                </div>
                <button className="button" type="button" disabled={query.isFetching} onClick={() => void query.refetch()}>
                    <RefreshCw size={14}/>{query.isFetching ? 'Checking' : 'Re-check'}
                </button>
            </div>

            <div className="content diagnostics">
                {query.isLoading && <p className="muted padded">Running diagnostics</p>}
                {query.error && <p className="error-text">Could not load diagnostics: {query.error.message}</p>}
                {report && <DiagnosticsReport report={report}/>}
            </div>
        </>
    )
}

function DiagnosticsReport({report}: {report: RuntimeDiagnostics}) {
    const emulated = report.emulatedServices
    const notRunning = emulated?.filter((service) => service.state !== 'running').length ?? 0
    const covered = emulated?.filter((service) => service.consolePages.length > 0).length ?? 0
    const reachable = report.runtime.status === 'reachable'

    return (
        <>
            <section className="console-summary" aria-label="Runtime summary">
                <div className={`summary-tile ${reachable ? 'ready' : 'unavailable'}`}>
                    <span>Runtime</span>
                    <strong>{reachable ? 'Reachable' : 'Unavailable'}</strong>
                    <small>{report.runtime.endpoint ?? 'No endpoint'}{report.runtime.latencyMs !== null ? ` · ${report.runtime.latencyMs} ms` : ''}</small>
                </div>
                <div className="summary-tile">
                    <span>Version</span>
                    <strong>{report.runtime.version ?? 'Unknown'}</strong>
                    <small>{report.runtime.edition ? `${report.runtime.edition} edition` : 'Not reported by the runtime'}</small>
                </div>
                <div className={`summary-tile ${notRunning > 0 ? 'pending' : ''}`}>
                    <span>Emulated services</span>
                    <strong>{emulated ? emulated.length : '—'}</strong>
                    <small>{emulated ? (notRunning > 0 ? `${notRunning} not running` : 'All running') : 'Not reported by the runtime'}</small>
                </div>
                <div className="summary-tile">
                    <span>Console coverage</span>
                    <strong>{emulated ? `${covered} / ${emulated.length}` : `${report.consoleServices.length}`}</strong>
                    <small>{emulated ? 'Emulated services with a console page' : 'Console services'}</small>
                </div>
            </section>

            {report.runtime.error && <p className="error-text">{report.runtime.error}</p>}

            <ConsoleServicesTable services={report.consoleServices}/>
            {emulated && <EmulatedServices services={emulated}/>}
            <ContainersTable report={report}/>
            <ConsoleProcess report={report}/>
        </>
    )
}

function ConsoleServicesTable({services}: {services: CloudServiceStatus[]}) {
    const [showResponding, setShowResponding] = useState(false)
    const failing = services.filter((service) => service.runtime !== 'reachable')
    const responding = services.filter((service) => service.runtime === 'reachable')
    const ordered = showResponding ? [...failing, ...responding] : failing
    return (
        <section className="table-panel" aria-labelledby="diagnostics-console-services">
            <header className="diagnostics-section-header">
                <h2 id="diagnostics-console-services">Console services</h2>
                <div className="diagnostics-filters">
                    <span className="muted">{failing.length ? `${failing.length} of ${services.length} failing` : `All ${services.length} responding`}</span>
                    {responding.length > 0 && (
                        <button className="button compact" type="button" aria-expanded={showResponding} onClick={() => setShowResponding((value) => !value)}>
                            {showResponding ? 'Hide responding' : `Show ${responding.length} responding`}
                        </button>
                    )}
                </div>
            </header>
            {services.length === 0 && <p className="muted padded">No console services are registered for this cloud.</p>}
            {ordered.length > 0 && <table className="table">
                    <thead><tr><th>Service</th><th>Status</th><th>Latency</th><th>Detail</th></tr></thead>
                    <tbody>{ordered.map((service) => (
                        <tr key={service.service}>
                            <td><code>{service.service}</code></td>
                            <td><span className={`status ${statusClass(service.runtime)}`}>{statusLabel(service.runtime)}</span></td>
                            <td>{service.latencyMs === null ? '—' : `${service.latencyMs} ms`}</td>
                            <td>{service.error ? <span className="error-text compact-text">{service.error}{service.errorCode ? ` (${service.errorCode})` : ''}</span> : <span className="muted">—</span>}</td>
                        </tr>
                    ))}</tbody>
                </table>}
        </section>
    )
}

function EmulatedServices({services}: {services: EmulatedServiceStatus[]}) {
    const [filter, setFilter] = useState<ServiceFilter>('all')
    const [search, setSearch] = useState('')
    const visible = useMemo(() => {
        const term = search.trim().toLowerCase()
        return services.filter((service) => {
            if (term && !service.name.includes(term) && !service.consolePages.some((page) => page.displayName.toLowerCase().includes(term))) return false
            if (filter === 'not-running') return service.state !== 'running'
            if (filter === 'with-page') return service.consolePages.length > 0
            if (filter === 'without-page') return service.consolePages.length === 0
            return true
        })
    }, [services, filter, search])

    return (
        <section className="table-panel" aria-labelledby="diagnostics-emulated-services">
            <header className="diagnostics-section-header">
                <h2 id="diagnostics-emulated-services">Emulated services</h2>
                <div className="diagnostics-filters">
                    <div className="diagnostics-filter-group" role="group" aria-label="Filter emulated services">
                        {SERVICE_FILTERS.map((option) => (
                            <button key={option.id} className={`button compact ${filter === option.id ? 'primary' : ''}`} type="button" aria-pressed={filter === option.id} onClick={() => setFilter(option.id)}>{option.label}</button>
                        ))}
                    </div>
                    <input className="input" type="search" value={search} onChange={(event) => setSearch(event.target.value)} placeholder="Filter services" aria-label="Filter emulated services by name"/>
                </div>
            </header>
            {visible.length === 0
                ? <p className="muted padded">No emulated services match this filter.</p>
                : <ul className="diagnostics-service-grid">{visible.map((service) => (
                    <li key={service.name} className="diagnostics-service">
                        <span className={`dot ${service.state === 'running' ? 'healthy' : 'unavailable'}`} aria-hidden="true"/>
                        <code>{service.name}</code>
                        {service.state !== 'running' && <span className="muted">{service.state}</span>}
                        {service.consolePages.map((page) => <Link key={page.service} className="diagnostics-page-link" to={page.route}>{page.displayName}</Link>)}
                    </li>
                ))}</ul>}
        </section>
    )
}

function ContainersTable({report}: {report: RuntimeDiagnostics}) {
    const containers = report.containers
    return (
        <section className="table-panel" aria-labelledby="diagnostics-containers">
            <header className="diagnostics-section-header">
                <h2 id="diagnostics-containers">Runtime containers</h2>
                <span className="muted">Containers started for EC2 instances</span>
            </header>
            {containers === null && <p className="muted padded">This runtime does not publish container diagnostics.</p>}
            {containers?.length === 0 && <p className="muted padded">No EC2 instance containers are running.</p>}
            {containers && containers.length > 0 && <table className="table">
                <thead><tr><th>Instance</th><th>Container</th><th>SSH</th></tr></thead>
                <tbody>{containers.map((container) => (
                    <tr key={container.resourceId}>
                        <td><Link to={`/cloud-explorer/${report.cloud}/compute?resource=${encodeURIComponent(container.resourceId)}`}><code>{container.resourceId}</code></Link></td>
                        <td>{container.status ?? '—'}</td>
                        <td>{container.sshPort ? <code>{container.sshHost ?? 'localhost'}:{container.sshPort}</code> : '—'}</td>
                    </tr>
                ))}</tbody>
            </table>}
        </section>
    )
}

function ConsoleProcess({report}: {report: RuntimeDiagnostics}) {
    return (
        <section className="table-panel" aria-labelledby="diagnostics-console">
            <header className="diagnostics-section-header">
                <h2 id="diagnostics-console">Console</h2>
            </header>
            <dl className="diagnostics-facts">
                <div><dt>Uptime</dt><dd>{formatUptime(report.console.uptimeSeconds)}</dd></div>
                <div><dt>Started</dt><dd>{formatDateTime(report.console.startedAt) ?? report.console.startedAt}</dd></div>
                <div><dt>Sign-in</dt><dd>{report.console.authMode === 'oidc' ? 'OIDC single sign-on' : 'Local administrator'}</dd></div>
                <div><dt>Active sessions</dt><dd>{report.console.activeSessions}</dd></div>
            </dl>
        </section>
    )
}

function formatUptime(totalSeconds: number): string {
    const days = Math.floor(totalSeconds / 86_400)
    const hours = Math.floor((totalSeconds % 86_400) / 3_600)
    const minutes = Math.floor((totalSeconds % 3_600) / 60)
    if (days > 0) return `${days} d ${hours} h`
    if (hours > 0) return `${hours} h ${minutes} min`
    if (minutes > 0) return `${minutes} min`
    return `${totalSeconds} s`
}

function statusClass(runtime: CloudServiceStatus['runtime']): string {
    if (runtime === 'reachable') return 'healthy'
    if (runtime === 'coming_soon') return 'degraded'
    return 'unavailable'
}

function statusLabel(runtime: CloudServiceStatus['runtime']): string {
    if (runtime === 'reachable') return 'Reachable'
    if (runtime === 'coming_soon') return 'Not registered'
    return 'Unavailable'
}

function normalizeCloud(value?: string): CloudProvider | null {
    return value === 'aws' || value === 'azure' || value === 'gcp' ? value : null
}