import type { FastifyInstance } from "fastify";
import type { AppConfig } from "../config.js";
import { loadSettings, saveSettings, type Settings } from "../settings/settings-store.js";
import { listWorkspaces, type ListModelsFn } from "./meta.js";

/** Merge stored settings over env/first-workspace defaults. */
export function effectiveSettings(cfg: AppConfig, stored: Settings): Settings {
  const workspaces = listWorkspaces(cfg.harnessDir);
  return {
    workspace: stored.workspace ?? (workspaces[0]?.name),
    provider: stored.provider ?? cfg.defaults.provider,
    model: stored.model ?? cfg.defaults.model,
    thinking: stored.thinking ?? cfg.defaults.thinking,
  };
}

export function settingsRoutes(
  app: FastifyInstance,
  deps: { cfg: AppConfig; listModels: ListModelsFn },
): void {
  app.get("/settings", async () => {
    return effectiveSettings(deps.cfg, loadSettings(deps.cfg));
  });

  app.put("/settings", async (req, reply) => {
    const b = (req.body ?? {}) as Settings;
    if (b.model) {
      let available: { id: string }[] = [];
      try {
        available = await deps.listModels();
      } catch {
        available = [];
      }
      // Only validate when Pi gave us a non-empty list; otherwise allow (degraded).
      if (available.length > 0 && !available.some((m) => m.id === b.model)) {
        return reply.code(400).send({ error: `Unknown model: ${b.model}` });
      }
    }
    const next: Settings = {
      workspace: b.workspace,
      provider: b.provider,
      model: b.model,
      thinking: b.thinking,
    };
    saveSettings(deps.cfg, next);
    return effectiveSettings(deps.cfg, next);
  });
}