import fs from "fs";
import path from "path";
import { DEFAULT_PROMPT_VERSION, PROMPTS_DIR } from "../config";
import type { PromptBundle, PromptPreset, PromptVersion } from "../types/preset";

function readPromptFile(relativePath: string): string {
  const filePath = path.resolve(PROMPTS_DIR, relativePath);
  if (!fs.existsSync(filePath)) {
    throw new Error(`Prompt file not found: ${filePath}`);
  }
  return fs.readFileSync(filePath, "utf-8").trim();
}

interface BuiltinPromptPresetDefinition {
  id: string;
  name: string;
  promptVersion: PromptVersion;
  schemaNotes: string;
  files: {
    system: string;
    developer: string;
    domain: string;
    fewshot: string;
  };
}

const BUILTIN_PROMPT_PRESETS: Record<PromptVersion, BuiltinPromptPresetDefinition> = {
  normalizer_v1: {
    id: "default-normalizer-v1",
    name: "Стандартный пресет NDC v1",
    promptVersion: "normalizer_v1",
    schemaNotes: "Используется схема normalized_query_v1. Строго соблюдать enum/required поля.",
    files: {
      system: path.join("system", "default.txt"),
      developer: path.join("developer", "default.txt"),
      domain: path.join("domain", "default.txt"),
      fewshot: path.join("fewshot", "default.txt")
    }
  },
  normalizer_v1_1: {
    id: "default-normalizer-v1_1",
    name: "Стандартный пресет NDC v1.1",
    promptVersion: "normalizer_v1_1",
    schemaNotes:
      "v1.1: усиленная taxonomy intent/route и confidence policy. Используется схема normalized_query_v1 без дополнительных полей.",
    files: {
      system: path.join("system", "default.txt"),
      developer: path.join("developer", "normalizer_v1_1.txt"),
      domain: path.join("domain", "normalizer_domain_v1_1.txt"),
      fewshot: path.join("fewshot", "normalizer_fewshot_v1_1.txt")
    }
  },
  normalizer_v1_1_1: {
    id: "default-normalizer-v1_1_1",
    name: "Стандартный пресет NDC v1.1.1",
    promptVersion: "normalizer_v1_1_1",
    schemaNotes:
      "v1.1.1: surgical patch для period_close_risk, exact drilldown requires и anomaly route escalation. Схема normalized_query_v1 без изменений.",
    files: {
      system: path.join("system", "default.txt"),
      developer: path.join("developer", "normalizer_v1_1_1.txt"),
      domain: path.join("domain", "normalizer_domain_v1_1.txt"),
      fewshot: path.join("fewshot", "normalizer_fewshot_v1_1_1.txt")
    }
  },
  normalizer_v1_1_2: {
    id: "default-normalizer-v1_1_2",
    name: "Стандартный пресет NDC v1.1.2",
    promptVersion: "normalizer_v1_1_2",
    schemaNotes:
      "v1.1.2: точечный patch границы heavy_analytical vs period_close_risk + confidence guard на boundary кейсах. Схема normalized_query_v1 без изменений.",
    files: {
      system: path.join("system", "default.txt"),
      developer: path.join("developer", "normalizer_v1_1_2.txt"),
      domain: path.join("domain", "normalizer_domain_v1_1.txt"),
      fewshot: path.join("fewshot", "normalizer_fewshot_v1_1_2.txt")
    }
  },
  normalizer_v1_1_2_1: {
    id: "default-normalizer-v1_1_2_1",
    name: "Стандартный пресет NDC v1.1.2.1",
    promptVersion: "normalizer_v1_1_2_1",
    schemaNotes:
      "v1.1.2.1: stable prompt baseline v1.1.2 + accounting-review phrasing anchors for 30-case validation pack. Схема normalized_query_v1 без изменений.",
    files: {
      system: path.join("system", "default.txt"),
      developer: path.join("developer", "normalizer_v1_1_2_1.txt"),
      domain: path.join("domain", "normalizer_domain_v1_1.txt"),
      fewshot: path.join("fewshot", "normalizer_fewshot_v1_1_2_1.txt")
    }
  },
  normalizer_v2: {
    id: "default-normalizer-v2",
    name: "Стандартный пресет NDC v2",
    promptVersion: "normalizer_v2",
    schemaNotes:
      "v2: decomposition-first pre-router. LLM returns fragments + scope + flags; deterministic routing happens in code. Схема normalized_query_v2.",
    files: {
      system: path.join("system", "default.txt"),
      developer: path.join("developer", "normalizer_v2.txt"),
      domain: path.join("domain", "normalizer_domain_v1_1.txt"),
      fewshot: path.join("fewshot", "normalizer_v2.txt")
    }
  },
  normalizer_v2_0_1: {
    id: "default-normalizer-v2_0_1",
    name: "Стандартный пресет NDC v2.0.1",
    promptVersion: "normalizer_v2_0_1",
    schemaNotes:
      "v2.0.1: clarification-threshold policy. Вопросы в контуре и с понятным route должны исполняться без лишних уточнений. Схема normalized_query_v2_0_1.",
    files: {
      system: path.join("system", "default.txt"),
      developer: path.join("developer", "normalizer_v2_0_1.txt"),
      domain: path.join("domain", "normalizer_domain_v1_1.txt"),
      fewshot: path.join("fewshot", "normalizer_v2_0_1.txt")
    }
  },
  normalizer_v2_0_2: {
    id: "default-normalizer-v2_0_2",
    name: "Стандартный пресет NDC v2.0.2",
    promptVersion: "normalizer_v2_0_2",
    schemaNotes:
      "v2.0.2: execution-state hardening + explicit route_status/no_route_reason. Схема normalized_query_v2_0_2.",
    files: {
      system: path.join("system", "default.txt"),
      developer: path.join("developer", "normalizer_v2_0_2.txt"),
      domain: path.join("domain", "normalizer_domain_v1_1.txt"),
      fewshot: path.join("fewshot", "normalizer_v2_0_2.txt")
    }
  }
};

function isPromptVersion(value: string | undefined): value is PromptVersion {
  return (
    value === "normalizer_v1" ||
    value === "normalizer_v1_1" ||
    value === "normalizer_v1_1_1" ||
    value === "normalizer_v1_1_2" ||
    value === "normalizer_v1_1_2_1" ||
    value === "normalizer_v2" ||
    value === "normalizer_v2_0_1" ||
    value === "normalizer_v2_0_2"
  );
}

function resolvePromptVersion(requested?: string): PromptVersion {
  if (isPromptVersion(requested)) {
    return requested;
  }
  if (isPromptVersion(DEFAULT_PROMPT_VERSION)) {
    return DEFAULT_PROMPT_VERSION;
  }
  return "normalizer_v2_0_2";
}

function loadBuiltinPreset(promptVersion: PromptVersion): PromptPreset {
  const now = new Date().toISOString();
  const definition = BUILTIN_PROMPT_PRESETS[promptVersion];
  return {
    id: definition.id,
    name: definition.name,
    createdAt: now,
    updatedAt: now,
    prompt_version: definition.promptVersion,
    systemPrompt: readPromptFile(definition.files.system),
    developerPrompt: readPromptFile(definition.files.developer),
    domainPrompt: readPromptFile(definition.files.domain),
    schemaNotes: definition.schemaNotes,
    fewShotExamples: readPromptFile(definition.files.fewshot)
  };
}

export function listBuiltinPromptPresets(): PromptPreset[] {
  return (Object.keys(BUILTIN_PROMPT_PRESETS) as PromptVersion[]).map((version) => loadBuiltinPreset(version));
}

export function loadDefaultPrompts(promptVersion?: string): PromptPreset {
  return loadBuiltinPreset(resolvePromptVersion(promptVersion));
}

export function buildPromptBundle(input: {
  promptVersion?: string;
  systemPrompt?: string;
  developerPrompt?: string;
  domainPrompt?: string;
  schemaNotes?: string;
  fewShotExamples?: string;
}): PromptBundle {
  const selectedPromptVersion = resolvePromptVersion(input.promptVersion);
  const defaults = loadDefaultPrompts(selectedPromptVersion);
  const systemPrompt = (input.systemPrompt ?? defaults.systemPrompt).trim();
  const developerPrompt = (input.developerPrompt ?? defaults.developerPrompt).trim();
  const domainPrompt = (input.domainPrompt ?? defaults.domainPrompt).trim();
  const schemaNotes = (input.schemaNotes ?? defaults.schemaNotes ?? "").trim();
  const fewShotExamples = (input.fewShotExamples ?? defaults.fewShotExamples ?? "").trim();
  const prompt_version = (input.promptVersion ?? defaults.prompt_version).trim() || selectedPromptVersion;

  const sections = [developerPrompt, `Schema notes:\n${schemaNotes}`];
  if (fewShotExamples) {
    sections.push(`Few-shot examples:\n${fewShotExamples}`);
  }

  return {
    prompt_version,
    systemPrompt,
    developerPrompt,
    domainPrompt,
    schemaNotes,
    fewShotExamples,
    combinedDeveloperPrompt: sections.join("\n\n")
  };
}