import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
import type { RefreshModelsContext } from "@earendil-works/pi-ai";
import { readFileSync, existsSync } from "node:fs";
import { join } from "node:path";
import { homedir } from "node:os";
import { loadSettings, resolveApiKeys, type ApiKey } from "./settings.js";
import { fetchPricing } from "./fetch.js";
import { fetchModelsDev } from "./fetch.js";
import { computeModels, type ComputedModels } from "./computeModels.js";
import { agentrouterConfigCommand } from "./command.js";
import { agentrouterMigrateCommand } from "./migrate.js";

function readAuthJson(): Record<string, AuthEntry> | null {
  const authPath = join(homedir(), ".pi", "agent", "auth.json");
  if (!existsSync(authPath)) return null;
  try {
    const raw = readFileSync(authPath, "utf-8");
    const parsed = JSON.parse(raw);
    if (typeof parsed !== "object" || parsed === null || Array.isArray(parsed)) return null;
    return parsed as Record<string, AuthEntry>;
  } catch {
    return null;
  }
}

interface AuthEntry {
  type: string;
  key: string;
}


function resolveAuthKeys(
  settings: { provider_prefix?: string },
  debug = false
): Array<{ id: string; key: string }> {
  const authData = readAuthJson();
  if (!authData) return [];

  const prefix = settings.provider_prefix ?? "agentrouter";

  const matches = Object.entries(authData)
    .filter(([name]) => name === prefix || name.startsWith(`${prefix}_`))
    .filter(([, entry]) => entry.type === "api_key" && typeof entry.key === "string" && entry.key.length > 0)
    .map(([name, entry]) => ({ id: name, key: entry.key }));

  if (matches.length > 0 && debug) {
    console.log("[agentrouter] auth.json entries:", matches.map((m) => m.id).join(", "));
  }

  return matches;
}

export default async function (pi: ExtensionAPI) {
  const settings = loadSettings(process.cwd());

  if (settings.debug) {
    console.log("[agentrouter] settings loaded:", JSON.stringify(settings, null, 2));
  }

  const apiKeys = resolveApiKeys(settings);

  if (settings.debug) {
    console.log("[agentrouter] api keys:", JSON.stringify(apiKeys, null, 2));
  }

  // ── auth.json discovery (hard cutover) ──────────────────────────────────

  const authKeys = resolveAuthKeys(settings, settings.debug);
  const usingAuthJson = authKeys.length > 0;

  if (usingAuthJson) {
    console.warn(
      "[agentrouter] api_keys in settings.json is deprecated. Using credentials from auth.json instead."
    );
  }

  // auth.json wins if it has matching entries; otherwise fall back to settings.json
  const keys = usingAuthJson ? authKeys : apiKeys;

  // If no API keys are configured, register a command to configure them
  if (keys.length === 0) {
    pi.registerCommand("agentrouter-config", {
      description: "Configure Agent Router settings",
      handler: async (args, ctx) => {
        await agentrouterConfigCommand(args, ctx);
      },
    });
    return;
  }

  // ── Fetch initial models at startup ─────────────────────────────────────

  let initialModels: ComputedModels = { anthropic: [], openai: [] };

  try {
    const pricing = await fetchPricing();
    const modelsDev = await fetchModelsDev();
    initialModels = computeModels(pricing, modelsDev, settings);
  } catch (err) {
    console.error("[agentrouter] initial model fetch failed:", err);
  }

  // ── Register providers ──────────────────────────────────────────────────

  // auth.json entries have meaningful names (e.g. "agentrouter_work"),
  // so we use the entry id directly as the provider name.
  // Fallback keys from settings.json keep the existing single/multi naming.
  const singleKey = !usingAuthJson && keys.length === 1;

  for (const { id, key } of keys) {
    const baseName = usingAuthJson ? id : singleKey ? "agentrouter" : `agentrouter_${id}`;
    const displayName = usingAuthJson ? id : singleKey ? "Agent Router" : `Agent Router (${id})`;

    if (settings.debug) {
      console.log(`[agentrouter] registering providers ${baseName} and ${baseName}_openai`);
    }

    // ── Anthropic provider ──────────────────────────────────────────────
    const anthropicProviderName = baseName;
    const anthropicConfig = {
      name: displayName,
      baseUrl: settings.api_base,
      api: "anthropic-messages" as const,
      models: initialModels.anthropic,
      authHeader: true,
      apiKey: key,
    };
    if (settings.debug) {
      console.log(`[agentrouter] provider config for ${anthropicProviderName}:`, JSON.stringify(anthropicConfig, null, 2));
    }
    pi.registerProvider(anthropicProviderName, {
      ...anthropicConfig,
      async refreshModels(_context: RefreshModelsContext) {
        try {
          const pricing = await fetchPricing();
          const modelsDev = await fetchModelsDev();
          return computeModels(pricing, modelsDev, settings).anthropic;
        } catch (err) {
          console.error(`[agentrouter] refreshModels failed for ${anthropicProviderName}:`, err);
          return [];
        }
      },
    });

    // ── OpenAI provider ────────────────────────────────────────────────
    const openaiProviderName = `${baseName}_openai`;
    const openaiConfig = {
      name: `${displayName} (OpenAI)`,
      baseUrl: `${settings.api_base}/v1`,
      api: "openai-completions" as const,
      models: initialModels.openai,
      authHeader: true,
      apiKey: key,
    };
    if (settings.debug) {
      console.log(`[agentrouter] provider config for ${openaiProviderName}:`, JSON.stringify(openaiConfig, null, 2));
    }
    pi.registerProvider(openaiProviderName, {
      ...openaiConfig,
      async refreshModels(_context: RefreshModelsContext) {
        try {
          const pricing = await fetchPricing();
          const modelsDev = await fetchModelsDev();
          return computeModels(pricing, modelsDev, settings).openai;
        } catch (err) {
          console.error(`[agentrouter] refreshModels failed for ${openaiProviderName}:`, err);
          return [];
        }
      },
    });
  }

  // Register the config command
  pi.registerCommand("agentrouter-config", {
    description: "Configure Agent Router settings",
    handler: async (args, ctx) => {
      await agentrouterConfigCommand(args, ctx);
    },
  });

  // Register migration command only when settings.json has api_keys to migrate
  const hasSettingsKeys = apiKeys.length > 0;
  if (hasSettingsKeys) {
    pi.registerCommand("agentrouter-migrate", {
      description: "Migrate api_keys from settings.json to auth.json",
      handler: async (args, ctx) => {
        await agentrouterMigrateCommand(args, ctx);
      },
    });
  }
}