/**
 * OpenCode v2 Plugin: Auto-discover models from OpenAI-compatible endpoints.
 *
 * Config-driven: iterates over the providers defined in opencode.jsonc and
 * discovers models for every provider whose `package` contains "openai-compatible"
 * AND which has opted in via `settings.discover_models === true`
 * (compat: `settings.modelsDiscovery.enabled === true`).
 *
 * The plugin never creates providers itself — it only augments existing ones.
 * Discovered models are merged into the provider's existing models (dedup by id).
 */

import { Plugin, Model } from "@opencode/plugin";

interface Target {
  id: string;
  baseURL: string;
  apiKey: string;
}

function isOpenAICompatible(pkg: unknown): boolean {
  return typeof pkg === "string" && pkg.toLowerCase().includes("openai-compatible");
}

function hasOptIn(settings: Record<string, unknown>): boolean {
  if (settings.discover_models === true) return true;
  const md = settings.modelsDiscovery;
  if (md && typeof md === "object" && (md as Record<string, unknown>).enabled === true) {
    return true;
  }
  return false;
}

async function fetchModels(
  baseURL: string,
  apiKey: string
): Promise<Model.Info[]> {
  const headers: Record<string, string> = { "Content-Type": "application/json" };
  if (apiKey) {
    headers["Authorization"] = `Bearer ${apiKey}`;
  }

  const res = await fetch(`${baseURL}/models`, { headers });
  if (!res.ok) {
    throw new Error(`HTTP ${res.status} from ${baseURL}/models`);
  }

  const json = await res.json();
  const rawModels = (json.data || []) as Array<Record<string, unknown>>;

  return rawModels.map((m) => {
    const modelId = typeof m.id === "string" ? m.id : String(m.id);
    const contextLength =
      typeof m.context_length === "number" ? m.context_length : 131072;
    const maxTokens = typeof m.max_tokens === "number" ? m.max_tokens : 32768;
    const inputMods = Array.isArray(m.input_modalities)
      ? (m.input_modalities as string[])
      : ["text"];
    const outputMods = Array.isArray(m.output_modalities)
      ? (m.output_modalities as string[])
      : ["text"];

    return {
      id: modelId,
      modelID: modelId,
      providerID: "", // filled in by caller
      name: modelId,
      capabilities: {
        tools: true,
        input: inputMods,
        output: outputMods,
      },
      variants: [],
      cost: [{ input: 0, output: 0, cache: { read: 0, write: 0 } }],
      limit: {
        context: contextLength,
        output: Math.min(maxTokens, contextLength),
      },
      time: {
        released: Math.floor(Date.now() / 1000),
      },
      status: "active" as const,
      enabled: true,
    } as unknown as Model.Info;
  });
}

export default Plugin.define({
  id: "opencode.openai-compatible-model-discovery",

  async setup(ctx) {
    // 1. Collect discovery targets from configured providers (sync).
    const targets: Target[] = [];
    try {
      await ctx.provider.transform((editor) => {
        for (const rec of editor.list()) {
          const info = rec.provider as Record<string, unknown>;
          if (!isOpenAICompatible(info.package)) continue;
          const settings =
            info.settings && typeof info.settings === "object"
              ? (info.settings as Record<string, unknown>)
              : {};
          if (!hasOptIn(settings)) continue;
          const baseURL =
            typeof settings.baseURL === "string" ? settings.baseURL : undefined;
          if (!baseURL) {
            console.warn(
              `[openai-discovery] Provider "${info.id}" has no settings.baseURL — skipping`
            );
            continue;
          }
          const apiKey =
            typeof settings.apiKey === "string" ? settings.apiKey : "";
          targets.push({ id: String(info.id), baseURL, apiKey });
        }
      });
    } catch (error) {
      console.error(
        `[openai-discovery] Failed to read providers: ${error instanceof Error ? error.message : String(error)}`
      );
      return;
    }

    if (targets.length === 0) {
      console.log(
        "[openai-discovery] No opted-in openai-compatible providers found — nothing to do"
      );
      return;
    }

    // 2. Discover + merge per target (isolated errors).
    for (const target of targets) {
      try {
        const models = await fetchModels(target.baseURL, target.apiKey);
        // stamp providerID
        for (const m of models) {
          (m as { providerID: string }).providerID = target.id;
        }

        await ctx.provider.transform((editor) => {
          const source = editor.get(target.id);
          if (!source) {
            console.warn(
              `[openai-discovery] Provider "${target.id}" no longer exists — skipping merge`
            );
            return;
          }
          const existing = [...source.models.values()];
          const existingIDs = new Set(existing.map((model) => String(model.id)));
          const merged = [
            ...existing,
            ...models.filter((m) => !existingIDs.has(String(m.id))),
          ];
          editor.models.set(target.id, merged);
        });

        console.log(
          `[openai-discovery] Registered ${models.length} models in provider "${target.id}"`
        );
      } catch (error) {
        console.error(
          `[openai-discovery] Failed to discover models for "${target.id}": ${error instanceof Error ? error.message : String(error)}`
        );
      }
    }
  },
});