export const dynamic = 'force-dynamic'

import { NextResponse } from 'next/server'
import { createClient } from '@/lib/supabase/server'
import { createAnthropicClient } from '@/lib/claude/client'
import { getApiKey } from '@/lib/settings'

type ZoneAggregate = {
  zone: string
  site: string
  total: number
  near_miss: number
  hazard: number
  injury: number
  avg_severity: number | null
  first_half: number
  second_half: number
}

export async function POST() {
  const supabase = await createClient()
  const { data: { user }, error: authError } = await supabase.auth.getUser()
  if (authError || !user) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })

  const { data: profile } = await supabase.from('users').select('role').eq('id', user.id).single()
  if (!profile || !['hse', 'admin', 'management'].includes(profile.role))
    return NextResponse.json({ error: 'Forbidden' }, { status: 403 })

  const now = new Date()
  const ninetyDaysAgo = new Date(now)
  ninetyDaysAgo.setDate(now.getDate() - 90)
  const midpoint = new Date(now)
  midpoint.setDate(now.getDate() - 45)

  const { data: incidents } = await supabase
    .from('incidents')
    .select('incident_type, severity, reported_at, zones (name), sites (name)')
    .gte('reported_at', ninetyDaysAgo.toISOString())

  const rows = incidents ?? []
  if (rows.length === 0)
    return NextResponse.json({ flags: [], summary: 'No incidents in the last 90 days.' })

  const zoneMap = new Map<string, ZoneAggregate & { severitySum: number; severityCount: number }>()
  for (const r of rows) {
    const zone = (r.zones as unknown as { name: string } | null)?.name ?? 'Unknown zone'
    const site = (r.sites as unknown as { name: string } | null)?.name ?? 'Unknown site'
    const key = `${site}|${zone}`
    let agg = zoneMap.get(key)
    if (!agg) {
      agg = {
        zone, site, total: 0, near_miss: 0, hazard: 0, injury: 0,
        avg_severity: null, first_half: 0, second_half: 0, severitySum: 0, severityCount: 0,
      }
      zoneMap.set(key, agg)
    }
    agg.total++
    if (r.incident_type === 'near_miss') agg.near_miss++
    if (r.incident_type === 'hazard') agg.hazard++
    if (r.incident_type === 'injury') agg.injury++
    if (typeof r.severity === 'number') {
      agg.severitySum += r.severity
      agg.severityCount++
    }
    if (new Date(r.reported_at as string) < midpoint) agg.first_half++
    else agg.second_half++
  }

  const aggregates: ZoneAggregate[] = [...zoneMap.values()].map(a => ({
    zone: a.zone,
    site: a.site,
    total: a.total,
    near_miss: a.near_miss,
    hazard: a.hazard,
    injury: a.injury,
    avg_severity: a.severityCount > 0 ? Math.round((a.severitySum / a.severityCount) * 10) / 10 : null,
    first_half: a.first_half,
    second_half: a.second_half,
  }))

  // Rate limit: 1 AI call per 60s per user (checked via audit_log)
  const { data: lastCall } = await supabase
    .from('audit_log')
    .select('changed_at')
    .eq('changed_by', user.id)
    .eq('action', 'ai_risk_flags')
    .order('changed_at', { ascending: false })
    .limit(1)
    .single()

  if (lastCall && Date.now() - new Date(lastCall.changed_at).getTime() < 60_000) {
    return NextResponse.json({ error: 'Rate limit: wait 60 seconds between AI requests' }, { status: 429 })
  }

  const anthropicKey = await getApiKey(supabase, 'ANTHROPIC_API_KEY')
  const anthropic = createAnthropicClient(anthropicKey)

  let message: Awaited<ReturnType<typeof anthropic.messages.create>>
  try {
    message = await anthropic.messages.create({
      model: 'claude-opus-4-8',
      thinking: { type: 'adaptive' },
      max_tokens: 2048,
      tools: [{
        name: 'flag_rising_risk',
        description: 'Flag warehouse zones showing rising safety risk from 90-day incident aggregates',
        input_schema: {
          type: 'object' as const,
          properties: {
            flags: {
              type: 'array',
              items: {
                type: 'object',
                properties: {
                  zone: { type: 'string' },
                  site: { type: 'string' },
                  risk_level: { type: 'string', enum: ['low', 'medium', 'high'] },
                  rationale: { type: 'string', description: 'One or two sentences citing the numbers' },
                  recommended_action: { type: 'string', description: 'One concrete preventive action' },
                },
                required: ['zone', 'site', 'risk_level', 'rationale', 'recommended_action'],
              },
            },
            summary: { type: 'string', description: 'Two-sentence overall risk picture' },
          },
          required: ['flags', 'summary'],
        },
      }],
      tool_choice: { type: 'tool', name: 'flag_rising_risk' },
      messages: [{
        role: 'user',
        content: `You are an HSE risk analyst for a Malaysian 3PL warehouse operator. Below are 90-day incident aggregates per zone. "first_half" is incidents in days 90-46, "second_half" is days 45-0 — a rising second_half means worsening trend. Near-miss and hazard reports are leading indicators; injuries are lagging.

Flag zones with rising or elevated risk (at most 5 flags; do not flag healthy zones). Base every rationale strictly on the numbers given.

<zone_data>
${JSON.stringify(aggregates, null, 2)}
</zone_data>`,
      }],
    })
  } catch {
    return NextResponse.json({ error: 'AI service unavailable' }, { status: 503 })
  }

  const toolBlock = message.content.find(b => b.type === 'tool_use')
  if (!toolBlock || toolBlock.type !== 'tool_use')
    return NextResponse.json({ error: 'AI suggestion failed' }, { status: 500 })

  const input = toolBlock.input as { flags?: unknown; summary?: unknown }
  if (!Array.isArray(input.flags) || typeof input.summary !== 'string')
    return NextResponse.json({ error: 'AI returned unexpected structure' }, { status: 500 })

  const flags = input.flags.filter(
    (f: unknown): f is { zone: string; site: string; risk_level: string; rationale: string; recommended_action: string } =>
      typeof f === 'object' && f !== null &&
      typeof (f as Record<string, unknown>).zone === 'string' &&
      typeof (f as Record<string, unknown>).site === 'string' &&
      ['low', 'medium', 'high'].includes((f as Record<string, unknown>).risk_level as string) &&
      typeof (f as Record<string, unknown>).rationale === 'string' &&
      typeof (f as Record<string, unknown>).recommended_action === 'string',
  )

  await supabase.rpc('write_audit_log', {
    p_table_name: 'incidents',
    p_record_id: user.id,
    p_action: 'ai_risk_flags',
    p_new_value: { flags, summary: input.summary, model: 'claude-opus-4-8' } as never,
  })

  return NextResponse.json({ flags, summary: input.summary })
}