export const dynamic = 'force-dynamic'

import { NextResponse } from 'next/server'
import { getSession } from '@/lib/auth/get-session'
import { withUser, asAdmin } from '@/lib/db/with-user'
import { writeAuditLog } from '@/lib/db/audit'
import { incidents, sites, zones, auditLog } from '@/lib/db/schema'
import { eq, and, gte, desc } from 'drizzle-orm'
import { createDeepSeekClient } 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 session = await getSession()
  if (!session) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
  if (!['hse', 'admin', 'management'].includes(session.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 rows = await withUser(session.sub, async tx =>
    tx.select({
      incidentType: incidents.incidentType,
      severity: incidents.severity,
      reportedAt: incidents.reportedAt,
      zoneName: zones.name,
      siteName: sites.name,
    })
    .from(incidents)
    .leftJoin(zones, eq(incidents.zoneId, zones.id))
    .leftJoin(sites, eq(incidents.siteId, sites.id))
    .where(gte(incidents.reportedAt, ninetyDaysAgo))
  )

  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.zoneName ?? 'Unknown zone'
    const site = r.siteName ?? '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.incidentType === 'near_miss') agg.near_miss++
    if (r.incidentType === 'hazard') agg.hazard++
    if (r.incidentType === 'injury') agg.injury++
    if (typeof r.severity === 'number') {
      agg.severitySum += r.severity
      agg.severityCount++
    }
    if (r.reportedAt && new Date(r.reportedAt) < 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 [lastCall] = await asAdmin(db =>
    db.select({ changedAt: auditLog.changedAt })
      .from(auditLog)
      .where(and(
        eq(auditLog.changedBy, session.sub),
        eq(auditLog.action, 'ai_risk_flags'),
      ))
      .orderBy(desc(auditLog.changedAt))
      .limit(1)
  )

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

  const deepseekKey = await getApiKey('DEEPSEEK_API_KEY')
  const client = createDeepSeekClient(deepseekKey)

  let res: Awaited<ReturnType<typeof client.chat.completions.create>>
  try {
    res = await client.chat.completions.create({
      model: 'deepseek-v4-pro',
      max_tokens: 2048,
      messages: [
        {
          role: 'system',
          content: `You are an HSE risk analyst for a Malaysian 3PL warehouse operator. You must respond with valid JSON only — no markdown, no explanation outside the JSON object.

Output exactly this JSON structure:
{
  "flags": [
    {
      "zone": "string",
      "site": "string",
      "risk_level": "low" | "medium" | "high",
      "rationale": "One or two sentences citing the numbers",
      "recommended_action": "One concrete preventive action"
    }
  ],
  "summary": "Two-sentence overall risk picture"
}

Flag only zones with rising or elevated risk (at most 5 flags; do not flag healthy zones). Base every rationale strictly on the numbers given. "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.`,
        },
        {
          role: 'user',
          content: `Below are 90-day incident aggregates per zone. Respond with JSON only.\n\n<zone_data>\n${JSON.stringify(aggregates, null, 2)}\n</zone_data>`,
        },
      ],
    })
  } catch (err) {
    console.error('DeepSeek risk-flags error:', err)
    return NextResponse.json({ error: 'AI service unavailable' }, { status: 503 })
  }

  const raw = res.choices[0]?.message?.content
  if (!raw) return NextResponse.json({ error: 'AI returned empty response' }, { status: 500 })

  // Strip markdown code fences if present
  const json = raw.replace(/^```(?:json)?\s*/i, '').replace(/\s*```$/i, '').trim()

  let input: { flags?: unknown; summary?: unknown }
  try { input = JSON.parse(json) }
  catch { return NextResponse.json({ error: 'AI returned unexpected structure' }, { status: 500 }) }

  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 withUser(session.sub, async tx =>
    writeAuditLog(tx, 'incidents', session.sub, 'ai_risk_flags',
      { flags, summary: input.summary, model: 'deepseek-v4-pro' })
  )

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