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-v4-pro',
      max_tokens: 2048,
      messages: [
        {
          role: 'system',
          content: `You are an experienced HSE investigator for a Malaysian 3PL warehouse. Draft a 5-Why root cause analysis for incidents. You must respond with valid JSON only — no markdown, no explanation outside the JSON object.

Output exactly this JSON structure:
{
  "five_why_steps": [
    { "why": "<the why question>", "answer": "<the finding or answer>" }
  ],
  "root_cause_summary": "<one-sentence root cause statement>",
  "capa_suggestions": ["<up to 3 corrective/preventive actions>"]
}

Provide 3–5 Why steps drilling from immediate cause to root cause. Frame CAPA suggestions appropriate for a Malaysian warehouse context.`,
        },
        {
          role: 'user',
          content: `Draft a 5-Why root cause analysis for this incident. Respond with JSON only.\n\nSite: ${incident.siteName ?? 'Unknown'}\nZone: ${incident.zoneName ?? 'Unknown'}\nIncident type: ${incident.incidentType}\nDescription: ${incident.description}\nSeverity: ${incident.severity ?? 'not yet assigned'}/5\nInjury involved: ${incident.injuryInvolved ? `yes — ${incident.medicalStatus}` : 'no'}\nFatality: ${incident.isFatality ? 'yes' : 'no'}\nSerious bodily injury: ${incident.isSeriousBodilyInjury ? 'yes' : 'no'}\nTriage notes: ${incident.triageNotes ?? 'none'}`,
        },
      ],
    })
  } catch {
    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 })

  const json = raw.replace(/^```(?:json)?\s*/i, '').replace(/\s*```$/i, '').trim()

  let draft: { five_why_steps?: unknown; root_cause_summary?: unknown; capa_suggestions?: unknown }
  try { draft = JSON.parse(json) }
  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-v4-pro',
    })
  })

  return NextResponse.json(draft)
}