/**
 * POST /api/dimensions/import-existing: one-shot scan that backfills the
 * dimension_values registry from codes already present on journal lines.
 *
 * The settings toggle-on flow runs this ("Importera befintliga koder",
 * dev_docs/dimensions_implementation_plan.md §4): every {sie_dim_no: code}
 * entry found in journal_entry_lines.dimensions that lacks a registry row gets
 * one created with is_active = false and name = code: referential validity
 * holds retroactively without polluting pickers. Dimensions missing from the
 * registry entirely (e.g. a custom dim number written via the v1 API) are
 * created too, so no line code is skipped. Idempotent: re-running creates
 * nothing new.
 *
 * Response: 200 { created: number } (count of dimension_values created).
 */
import { NextResponse } from 'next/server'
import { ensureInitialized } from '@/lib/init'
import { withRouteContext } from '@/lib/api/with-route-context'
import { fetchEntryLines, type EntryLinesQuery } from '@/lib/bookkeeping/entry-lines'
import { errorResponse, errorResponseFromCode } from '@/lib/errors/get-structured-error'
import { getErrorMessage as getUserErrorMessage } from '@/lib/errors/get-error-message'

ensureInitialized()

interface LineRow {
  id: string
  dimensions: Record<string, string> | null
}

export const POST = withRouteContext(
  'dimension.import_existing',
  async (_request, ctx) => {
    const { supabase, companyId, log, requestId } = ctx

    const { error: ensureError } = await supabase.rpc('ensure_company_dimensions', {
      p_company_id: companyId,
    })
    if (ensureError) {
      log.error('ensure_company_dimensions failed', ensureError)
      return errorResponse(ensureError, log, { requestId })
    }

    try {
      // 1. Collect every {dim_no: code} pair used on this company's lines.
      //    journal_entry_lines has no company_id column, so the scope comes
      //    from the parent entries. Driving the query from that side
      //    (lib/bookkeeping/entry-lines.ts) instead of a
      //    `journal_entries!inner(company_id)` embed keeps PostgREST from
      //    compiling a correlated LATERAL join that walks every tenant's
      //    lines. The parent is not read here, so it is not reattached.
      const lines = await fetchEntryLines<LineRow>({
        supabase,
        lineColumns: 'id, dimensions',
        filterEntries: (q: EntryLinesQuery) => q.eq('company_id', companyId),
        filterLines: (q: EntryLinesQuery) => q.neq('dimensions', '{}'),
        attachEntriesAs: null,
      })

      const codesByDimNo = new Map<number, Set<string>>()
      for (const line of lines) {
        if (!line.dimensions) continue
        for (const [key, code] of Object.entries(line.dimensions)) {
          const dimNo = Number(key)
          if (!Number.isInteger(dimNo) || dimNo < 1) continue
          if (typeof code !== 'string' || code.length === 0) continue
          // Sanitize exactly like the PR1 substrate backfill
          // (left(regexp_replace(code, '["{}]', '', 'g'), 40)) so candidates
          // satisfy the dimension_values code CHECK; codes that sanitize to
          // empty are dropped, and the Set de-duplicates post-sanitization.
          const sanitized = code.replace(/["{}]/g, '').slice(0, 40)
          if (sanitized.length === 0) continue
          const set = codesByDimNo.get(dimNo) ?? new Set<string>()
          set.add(sanitized)
          codesByDimNo.set(dimNo, set)
        }
      }

      if (codesByDimNo.size === 0) {
        return NextResponse.json({ created: 0 })
      }

      // 2. Registry state: dim_no → dimension_id, plus existing value codes.
      const { data: dims, error: dimsError } = await supabase
        .from('dimensions')
        .select('id, sie_dim_no')
        .eq('company_id', companyId)
      if (dimsError) throw dimsError

      const dimIdByNo = new Map<number, string>(
        ((dims ?? []) as { id: string; sie_dim_no: number }[]).map((d) => [d.sie_dim_no, d.id]),
      )

      // 3. Create registry rows for dim numbers seen on lines but missing from
      //    the registry (written via raw v1 JSON / MCP before the register
      //    existed). is_system=false; the user can rename them afterwards.
      const missingDimNos = [...codesByDimNo.keys()].filter((n) => !dimIdByNo.has(n))
      if (missingDimNos.length > 0) {
        // ignoreDuplicates: a concurrent creator (double-click, MCP) must not
        // abort the whole batch with a 23505: the survivor's row wins.
        const { data: createdDims, error: createDimsError } = await supabase
          .from('dimensions')
          .upsert(
            missingDimNos.map((n) => ({
              company_id: companyId,
              sie_dim_no: n,
              name: `Dimension ${n}`,
              is_system: false,
            })),
            { onConflict: 'company_id,sie_dim_no', ignoreDuplicates: true },
          )
          .select('id, sie_dim_no')
        if (createDimsError) throw createDimsError
        for (const d of (createdDims ?? []) as { id: string; sie_dim_no: number }[]) {
          dimIdByNo.set(d.sie_dim_no, d.id)
        }
      }

      const { data: existingValues, error: valuesError } = await supabase
        .from('dimension_values')
        .select('dimension_id, code')
        .eq('company_id', companyId)
      if (valuesError) throw valuesError

      const existing = new Set(
        ((existingValues ?? []) as { dimension_id: string; code: string }[]).map(
          (v) => `${v.dimension_id}\0${v.code}`,
        ),
      )

      // 4. Insert the missing values. name = code (the line map carries no
      //    display name), is_active = false so pickers stay clean until the
      //    user promotes the codes they still use.
      const inserts: Array<{
        company_id: string
        dimension_id: string
        code: string
        name: string
        is_active: boolean
      }> = []
      for (const [dimNo, codes] of codesByDimNo) {
        const dimensionId = dimIdByNo.get(dimNo)
        if (!dimensionId) continue
        for (const code of codes) {
          if (existing.has(`${dimensionId}\0${code}`)) continue
          inserts.push({
            company_id: companyId,
            dimension_id: dimensionId,
            code,
            name: code,
            is_active: false,
          })
        }
      }

      // Upsert with ignoreDuplicates so one duplicate row (raced insert, or a
      // code the existing-values snapshot missed) skips instead of aborting
      // the whole batch with a 23505. `created` counts the rows actually
      // inserted: the returned set excludes ignored duplicates.
      let created = 0
      if (inserts.length > 0) {
        const { data: insertedValues, error: insertError } = await supabase
          .from('dimension_values')
          .upsert(inserts, {
            onConflict: 'company_id,dimension_id,code',
            ignoreDuplicates: true,
          })
          .select('id')
        if (insertError) throw insertError
        created = (insertedValues ?? []).length
      }

      return NextResponse.json({ created })
    } catch (err) {
      log.error('dimension import-existing failed', err as Error)
      return errorResponseFromCode('DIMENSION_IMPORT_FAILED', log, {
        requestId,
        details: { reason: err instanceof Error ? getUserErrorMessage(err) : getUserErrorMessage(err) },
      })
    }
  },
  { requireWrite: true },
)