// 技能库纯逻辑：按 scope 分组、档位文案。
// 对齐 C3 扩（GET /skills，只读注册表视图）。纯逻辑，便于 node 环境单测。

import type { SkillView } from "@/lib/api/types";

export type SkillScope = "builtin" | "custom" | "community";

export const SCOPE_LABELS: Record<string, string> = {
  builtin: "内置",
  custom: "自定义",
  community: "社区",
};

export const TIER_LABELS: Record<string, string> = {
  writer: "写手",
  analyst: "分析",
  light: "轻量",
};

export function scopeLabel(scope: string): string {
  return SCOPE_LABELS[scope] ?? scope;
}

export function tierLabel(tier: string): string {
  return TIER_LABELS[tier] ?? tier;
}

export type SkillGroups = { scope: string; skills: SkillView[] }[];

export interface SkillCount {
  key: string;
  count: number;
}

export interface SkillsSummary {
  total: number;
  readonlyCount: number;
  writableCount: number;
  scopes: SkillCount[];
  tiers: SkillCount[];
  readableTables: string[];
  writableTables: string[];
}

// 按 scope 分组（保持服务端 name 升序）；scope 顺序按首次出现。
export function groupByScope(
  skills: readonly SkillView[] | undefined,
): SkillGroups {
  const order: string[] = [];
  const map = new Map<string, SkillView[]>();
  for (const skill of skills ?? []) {
    if (!map.has(skill.scope)) {
      order.push(skill.scope);
      map.set(skill.scope, []);
    }
    map.get(skill.scope)?.push(skill);
  }
  return order.map((scope) => ({ scope, skills: map.get(scope) ?? [] }));
}

export function summarizeSkills(
  skills: readonly SkillView[] | undefined,
): SkillsSummary {
  const scopeCounts = new Map<string, number>();
  const tierCounts = new Map<string, number>();
  const readableTables = new Set<string>();
  const writableTables = new Set<string>();
  let writableCount = 0;

  for (const skill of skills ?? []) {
    scopeCounts.set(skill.scope, (scopeCounts.get(skill.scope) ?? 0) + 1);
    tierCounts.set(skill.tier, (tierCounts.get(skill.tier) ?? 0) + 1);
    for (const table of skill.reads ?? []) {
      readableTables.add(table);
    }
    if (skill.writes && skill.writes.length > 0) {
      writableCount += 1;
      for (const table of skill.writes) {
        writableTables.add(table);
      }
    }
  }

  return {
    total: skills?.length ?? 0,
    readonlyCount: (skills?.length ?? 0) - writableCount,
    writableCount,
    scopes: countsFromMap(scopeCounts),
    tiers: countsFromMap(tierCounts),
    readableTables: [...readableTables].sort(),
    writableTables: [...writableTables].sort(),
  };
}

function countsFromMap(map: Map<string, number>): SkillCount[] {
  return [...map.entries()].map(([key, count]) => ({ key, count }));
}