export const dynamic = 'force-dynamic'

import { NextRequest, 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, auditLog, sites, zones } from '@/lib/db/schema'
import { eq, and, gte, sql } from 'drizzle-orm'
import { createDeepSeekClient } from '@/lib/claude/client'
import { getApiKey } from '@/lib/settings'

export async function POST(
  _request: NextRequest,
  { params }: { params: Promise<{ id: string }> }
) {
  const { id } = await params
  const session = await getSession()
  if (!session) return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
  if (!['hse', 'admin'].includes(session.role))
    return NextResponse.json({ error: 'Forbidden' }, { status: 403 })

  // Rate limit
  const since = new Date(Date.now() - 60_000)
  const [rateRow] = await asAdmin(db =>
    db.select({ cnt: sql<number>`count(*)` }).from(auditLog)
      .where(and(
        eq(auditLog.changedBy, session.sub),
        eq(auditLog.action, 'ai_rca_draft'),
        gte(auditLog.changedAt, since),
      ))
  )
  if (Number(rateRow?.cnt ?? 0) > 0)
    return NextResponse.json({ error: 'Rate limited — please wait 60 seconds' }, { status: 429 })

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

  const [incident] = await withUser(session.sub, async tx =>
    tx.select({
      incidentType: incidents.incidentType,
      description: incidents.description,
      severity: incidents.severity,
      injuryInvolved: incidents.injuryInvolved,
      medicalStatus: incidents.medicalStatus,
      isFatality: incidents.isFatality,
      isSeriousBodilyInjury: incidents.isSeriousBodilyInjury,
      triageNotes: incidents.triageNotes,
      siteName: sites.name,
      zoneName: zones.name,
    })
    .from(incidents)
    .leftJoin(sites, eq(incidents.siteId, sites.id))
    .leftJoin(zones, eq(incidents.zoneId, zones.id))
    .where(eq(incidents.id, id))
    .limit(1)
  )
  if (!incident) return NextResponse.json({ error: 'Not found' }, { status: 404 })

  let res: Awaited<ReturnType<typeof client.chat.completions.create>>
  try {
    res = await client.chat.completions.create({
      model: 'deepseek-chat',
      max_tokens: 2048,
      tools: [{
        type: 'function',
        function: {
          name: 'draft_rca',
          description: 'Draft a 5-Why root cause analysis and CAPA suggestions for an HSE incident',
          parameters: {
            type: 'object',
            properties: {
              five_why_steps: {
                type: 'array',
                items: {
                  type: 'object',
                  properties: {
                    why: { type: 'string', description: 'The why question' },
                    answer: { type: 'string', description: 'The finding or answer' },
                  },
                  required: ['why', 'answer'],
                },
                description: '3 to 5 why steps',
              },
              root_cause_summary: {
                type: 'string',
                description: 'One-sentence root cause statement',
              },
              capa_suggestions: {
                type: 'array',
                items: { type: 'string' },
                description: 'Up to 3 corrective/preventive action suggestions',
              },
            },
            required: ['five_why_steps', 'root_cause_summary', 'capa_suggestions'],
          },
        },
      }],
      tool_choice: { type: 'function', function: { name: 'draft_rca' } },
      messages: [{
        role: 'user',
        content: `You are an experienced HSE investigator for a Malaysian 3PL warehouse. Draft a 5-Why root cause analysis for this incident.

Site: ${incident.siteName ?? 'Unknown'}
Zone: ${incident.zoneName ?? 'Unknown'}
Incident type: ${incident.incidentType}
Description: ${incident.description}
Severity: ${incident.severity ?? 'not yet assigned'}/5
Injury involved: ${incident.injuryInvolved ? `yes — ${incident.medicalStatus}` : 'no'}
Fatality: ${incident.isFatality ? 'yes' : 'no'}
Serious bodily injury: ${incident.isSeriousBodilyInjury ? 'yes' : 'no'}
Triage notes: ${incident.triageNotes ?? 'none'}

Provide 3–5 Why steps drilling from immediate cause to root cause. Give a one-sentence root cause statement. Suggest 3 corrective/preventive actions appropriate for a Malaysian warehouse context.`,
      }],
    })
  } catch {
    return NextResponse.json({ error: 'AI service unavailable' }, { status: 503 })
  }

  const call = res.choices[0]?.message?.tool_calls?.[0]
  if (!call || call.type !== 'function') return NextResponse.json({ error: 'AI draft failed' }, { status: 500 })

  let draft: { five_why_steps?: unknown; root_cause_summary?: unknown; capa_suggestions?: unknown }
  try { draft = JSON.parse(call.function.arguments) }
  catch { return NextResponse.json({ error: 'AI returned unexpected structure' }, { status: 500 }) }

  if (
    !Array.isArray(draft.five_why_steps) ||
    typeof draft.root_cause_summary !== 'string' ||
    !Array.isArray(draft.capa_suggestions)
  ) {
    return NextResponse.json({ error: 'AI returned unexpected structure' }, { status: 500 })
  }

  await withUser(session.sub, async tx => {
    await writeAuditLog(tx, 'incidents', id, 'ai_rca_draft', {
      root_cause_summary: draft.root_cause_summary as string,
      model: 'deepseek-chat',
    })
  })

  return NextResponse.json(draft)
}