import type { AgentEvent } from '@/chat/types'

function normalizeTimestamp(value: number): Date {
    const ms = value < 1_000_000_000_000 ? value * 1000 : value
    return new Date(ms)
}

export function formatUnixTimestamp(value: number): string {
    const date = normalizeTimestamp(value)
    if (Number.isNaN(date.getTime())) return String(value)
    return date.toLocaleString()
}

export function formatResetTime(value: number): string {
    const date = normalizeTimestamp(value)
    if (Number.isNaN(date.getTime())) return String(value)

    const now = new Date()
    const isToday = date.getFullYear() === now.getFullYear()
        && date.getMonth() === now.getMonth()
        && date.getDate() === now.getDate()

    if (isToday) {
        return date.toLocaleTimeString(undefined, { hour: 'numeric', minute: '2-digit' })
    }
    return date.toLocaleString(undefined, { month: 'short', day: 'numeric', hour: 'numeric', minute: '2-digit' })
}

export function formatMessageTimestamp(date: Date, now: Date = new Date()): string {
    const sameDay = date.getFullYear() === now.getFullYear()
        && date.getMonth() === now.getMonth()
        && date.getDate() === now.getDate()

    if (sameDay) {
        return date.toLocaleTimeString(undefined, { hour: 'numeric', minute: '2-digit' })
    }

    const sameYear = date.getFullYear() === now.getFullYear()
    if (sameYear) {
        return date.toLocaleString(undefined, { month: 'short', day: 'numeric', hour: 'numeric', minute: '2-digit' })
    }

    return date.toLocaleString(undefined, { year: 'numeric', month: 'short', day: 'numeric', hour: 'numeric', minute: '2-digit' })
}

export function formatMessageTimestampTitle(date: Date): string {
    return date.toLocaleString(undefined, {
        year: 'numeric',
        month: 'short',
        day: 'numeric',
        hour: 'numeric',
        minute: '2-digit',
        second: '2-digit'
    })
}

// Known types: five_hour → "5-hour", seven_day → "7-day".
// Unknown types use underscore-to-space fallback (e.g. thirty_day → "thirty day").
function formatLimitType(limitType: string | undefined): string {
    if (!limitType) return ''
    if (limitType === 'five_hour') return '5-hour'
    if (limitType === 'seven_day') return '7-day'
    return limitType.replace(/_/g, ' ')
}

function formatDuration(ms: number): string {
    const seconds = ms / 1000
    if (seconds < 60) return `${seconds.toFixed(1)}s`
    const mins = Math.floor(seconds / 60)
    const secs = Math.round(seconds % 60)
    return `${mins}m ${secs}s`
}

function asRecord(value: unknown): Record<string, unknown> | null {
    return value && typeof value === 'object' ? value as Record<string, unknown> : null
}

function asNumber(value: unknown): number | null {
    return typeof value === 'number' && Number.isFinite(value) ? value : null
}

function formatTokenCount(value: number): string {
    if (value >= 1_000_000) return `${(value / 1_000_000).toFixed(1)}M`
    if (value >= 10_000) return `${(value / 1_000).toFixed(1)}k`
    if (value >= 1_000) return `${Math.round(value / 1_000)}k`
    return String(value)
}

function formatGoalStatus(status: string): string {
    if (status === 'active') return 'active'
    if (status === 'paused') return 'paused'
    if (status === 'budgetLimited') return 'limited by budget'
    if (status === 'complete') return 'complete'
    return status
}

function formatThreadGoalEvent(event: AgentEvent): EventPresentation {
    const goal = asRecord((event as Record<string, unknown>).goal)
    if (!goal) return { icon: null, text: 'Goal updated' }
    const status = typeof goal.status === 'string' ? goal.status : 'updated'
    const tokensUsed = asNumber(goal.tokensUsed ?? goal.tokens_used)
    const tokenBudget = asNumber(goal.tokenBudget ?? goal.token_budget)
    const parts = [`Goal ${formatGoalStatus(status)}`]
    if (tokensUsed !== null && tokenBudget !== null) {
        parts.push(`${formatTokenCount(tokensUsed)} / ${formatTokenCount(tokenBudget)}`)
    }
    return { icon: null, text: parts.join(' · ') }
}

function formatTokenCountEvent(event: AgentEvent): EventPresentation {
    const info = asRecord((event as Record<string, unknown>).info)
    const total = asRecord(info?.total) ?? info
    if (!total) return { icon: '◷', text: 'Context updated' }

    const inputTokens = asNumber(total.inputTokens ?? total.input_tokens)
    const outputTokens = asNumber(total.outputTokens ?? total.output_tokens)
    const cachedTokens = asNumber(total.cachedInputTokens ?? total.cacheReadInputTokens ?? total.cache_read_input_tokens)
    const reasoningTokens = asNumber(total.reasoningOutputTokens ?? total.reasoning_output_tokens)
    const contextWindow = asNumber(info?.modelContextWindow ?? info?.model_context_window)

    const parts: string[] = []
    if (inputTokens !== null && contextWindow !== null) {
        const pct = Math.round((inputTokens / contextWindow) * 100)
        parts.push(`Context ${formatTokenCount(inputTokens)} / ${formatTokenCount(contextWindow)} (${pct}%)`)
    } else if (inputTokens !== null) {
        parts.push(`Context ${formatTokenCount(inputTokens)}`)
    } else {
        parts.push('Context updated')
    }

    if (outputTokens !== null) parts.push(`out ${formatTokenCount(outputTokens)}`)
    if (cachedTokens !== null && cachedTokens > 0) parts.push(`cached ${formatTokenCount(cachedTokens)}`)
    if (reasoningTokens !== null && reasoningTokens > 0) parts.push(`reasoning ${formatTokenCount(reasoningTokens)}`)

    return { icon: '◷', text: parts.join(' · ') }
}

export type EventPresentation = {
    icon: string | null
    text: string
}

export function getEventPresentation(event: AgentEvent): EventPresentation {
    if (event.type === 'api-error') {
        const { retryAttempt, maxRetries } = event as { retryAttempt: number; maxRetries: number }
        if (maxRetries > 0 && retryAttempt >= maxRetries) {
            return { icon: '⚠️', text: 'API error: Max retries reached' }
        }
        if (maxRetries > 0) {
            return { icon: '⏳', text: `API error: Retrying (${retryAttempt}/${maxRetries})` }
        }
        if (retryAttempt > 0) {
            return { icon: '⏳', text: 'API error: Retrying...' }
        }
        return { icon: '⚠️', text: 'API error' }
    }
    if (event.type === 'switch') {
        const mode = event.mode === 'local' ? 'local' : 'remote'
        return { icon: '🔄', text: `Switched to ${mode}` }
    }
    if (event.type === 'title-changed') {
        const title = typeof event.title === 'string' ? event.title : ''
        return { icon: null, text: title ? `Title changed to "${title}"` : 'Title changed' }
    }
    if (event.type === 'permission-mode-changed') {
        const modeValue = (event as Record<string, unknown>).mode
        const mode = typeof modeValue === 'string' ? modeValue : 'default'
        return { icon: '🔐', text: `Permission mode: ${mode}` }
    }
    if (event.type === 'limit-warning') {
        const ev = event as { utilization?: number; endsAt?: number; limitType?: string }
        const pct = Math.round((ev.utilization ?? 0) * 100)
        const endsAt = typeof ev.endsAt === 'number' ? ev.endsAt : null
        const typeLabel = formatLimitType(ev.limitType)
        const suffix = typeLabel ? ` (${typeLabel})` : ''
        return { icon: '⚠️', text: endsAt ? `Usage limit ${pct}%${suffix} · resets ${formatResetTime(endsAt)}` : `Usage limit ${pct}%${suffix}` }
    }
    if (event.type === 'limit-reached') {
        const ev = event as { endsAt?: number; limitType?: string }
        const endsAt = typeof ev.endsAt === 'number' ? ev.endsAt : null
        const typeLabel = formatLimitType(ev.limitType)
        const suffix = typeLabel ? ` (${typeLabel})` : ''
        return { icon: '⏳', text: endsAt ? `Usage limit reached${suffix} until ${formatUnixTimestamp(endsAt)}` : `Usage limit reached${suffix}` }
    }
    if (event.type === 'error') {
        return { icon: '⚠️', text: typeof event.message === 'string' ? event.message : 'Error' }
    }
    if (event.type === 'message') {
        return { icon: null, text: typeof event.message === 'string' ? event.message : 'Message' }
    }
    if (event.type === 'turn-duration') {
        const ms = typeof event.durationMs === 'number' ? event.durationMs : 0
        return { icon: '⏱️', text: `Turn: ${formatDuration(ms)}` }
    }
    if (event.type === 'microcompact') {
        const saved = typeof event.tokensSaved === 'number' ? event.tokensSaved : 0
        const formatted = saved >= 1000 ? `${Math.round(saved / 1000)}K` : String(saved)
        return { icon: '📦', text: `Context compacted (saved ${formatted} tokens)` }
    }
    if (event.type === 'compact') {
        return { icon: '📦', text: 'Conversation compacted' }
    }
    if (event.type === 'thread-goal-updated') {
        return formatThreadGoalEvent(event)
    }
    if (event.type === 'thread-goal-cleared') {
        return { icon: null, text: 'Goal cleared' }
    }
    if (event.type === 'token-count') {
        return formatTokenCountEvent(event)
    }
    try {
        return { icon: null, text: JSON.stringify(event) }
    } catch {
        return { icon: null, text: String(event.type) }
    }
}

export function renderEventLabel(event: AgentEvent): string {
    return getEventPresentation(event).text
}