/**
 * Training / style corpus hooks.
 *
 * Endpoints touched (all under /api/training/):
 *   - GET /style-report → the dashboard payload (corpus stats + anatomy
 *     + signature phrases + per-decision contribution)
 *   - GET /corpus → flat list of decisions for the corpus tab / compare tool
 *   - GET /compare?a=UUID&b=UUID → side-by-side comparison
 *   - DELETE /corpus/{id} → remove a decision from the corpus
 */

import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
import { apiRequest } from "./client";

export type StyleReport = {
  corpus: {
    decision_count: number;
    total_chars: number;
    avg_chars: number;
    date_range: [string | null, string | null];
    decisions: Array<{
      number: string;
      date: string;
      chars: number;
      subjects: string[];
    }>;
    subject_distribution: Array<{ label: string; count: number }>;
    headline: string;
  };
  anatomy: {
    sections: Array<{
      type: string;
      label: string;
      avg_chars: number;
      pct: number;
      coverage: number;
    }>;
    total_coverage: number;
    headline: string;
  };
  signature_phrases: {
    items: Array<{
      type: string;
      text: string;
      context: string;
      frequency: number;
      examples: string[];
    }>;
    total_decisions: number;
    top_display: string;
    headline: string;
  };
  contribution: {
    growth_curve: Array<{
      decision_number: string;
      date: string;
      cumulative: number;
    }>;
    decision_contributions: unknown[];
    total_patterns: number;
    headline: string;
  };
};

export type CorpusDecision = {
  id: string;
  decision_number: string;
  decision_date: string;
  subject_categories: string[];
  chars: number;
  created_at: string;
};

export type CompareResult = {
  a: CompareSide;
  b: CompareSide;
  shared: PatternEntry[];
  only_a: PatternEntry[];
  only_b: PatternEntry[];
};

export type CompareSide = {
  id: string;
  decision_number: string;
  decision_date: string;
  chars: number;
  subjects: string[];
  sections: Array<{ type: string; chars: number }>;
  patterns_count: number;
};

export type PatternEntry = {
  id: string;
  type: string;
  text: string;
  context: string;
};

export const trainingKeys = {
  all: ["training"] as const,
  report: () => [...trainingKeys.all, "style-report"] as const,
  corpus: () => [...trainingKeys.all, "corpus"] as const,
  compare: (a: string, b: string) =>
    [...trainingKeys.all, "compare", a, b] as const,
};

export function useStyleReport() {
  return useQuery({
    queryKey: trainingKeys.report(),
    queryFn: ({ signal }) =>
      apiRequest<StyleReport>("/api/training/style-report", { signal }),
    staleTime: 60_000,
  });
}

export function useCorpus() {
  return useQuery({
    queryKey: trainingKeys.corpus(),
    queryFn: ({ signal }) =>
      apiRequest<CorpusDecision[]>("/api/training/corpus", { signal }),
    staleTime: 60_000,
  });
}

export function useCompare(a: string | null, b: string | null) {
  return useQuery({
    queryKey: trainingKeys.compare(a ?? "", b ?? ""),
    queryFn: ({ signal }) =>
      apiRequest<CompareResult>(
        `/api/training/compare?a=${encodeURIComponent(a!)}&b=${encodeURIComponent(b!)}`,
        { signal },
      ),
    enabled: Boolean(a && b && a !== b),
    staleTime: Infinity,
  });
}

export function useDeleteCorpusEntry() {
  const qc = useQueryClient();
  return useMutation({
    mutationFn: (id: string) =>
      apiRequest<{ deleted: boolean }>(
        `/api/training/corpus/${encodeURIComponent(id)}`,
        { method: "DELETE" },
      ),
    onSuccess: () => {
      qc.invalidateQueries({ queryKey: trainingKeys.corpus() });
      qc.invalidateQueries({ queryKey: trainingKeys.report() });
    },
  });
}