import type { FastifyInstance } from "fastify";
import type { AppConfig } from "../config.js";
import type { Settings } from "../settings/settings-store.js";
import { listWorkspaces, type ListModelsFn } from "./meta.js";
import type { PrincipalContext } from "../auth/principal.js";
import { isPrincipalContext, requirePermission } from "../auth/authorization.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: cfg.defaults.provider ?? stored.provider,
    model: cfg.defaults.model ?? stored.model,
    thinking: cfg.defaults.thinking ?? stored.thinking,
  };
}

export function settingsRoutes(
  app: FastifyInstance,
  deps: {
    cfg: AppConfig; listModels: ListModelsFn;
    getSettings: (principal: PrincipalContext) => Promise<Settings>;
  },
): void {
  app.get("/settings", async (req, reply) => {
    const principal = requirePermission(req, reply, "session.use");
    if (!isPrincipalContext(principal)) return principal;
    try {
      return await deps.getSettings(principal);
    } catch {
      return reply.code(503).send({ error: "settings storage is unavailable" });
    }
  });

  app.put("/settings", async (req, reply) => {
    const principal = requirePermission(req, reply, "settings.manage");
    if (!isPrincipalContext(principal)) return principal;
    const b = (req.body ?? {}) as Settings;
    if (b.model) {
      let available: { provider: string; 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(
        (candidate) => candidate.provider === b.provider && candidate.id === b.model,
      )) {
        return reply.code(400).send({
          error: `Unknown model: ${b.provider ?? "unknown"}/${b.model}`,
        });
      }
    }
    try {
      // Retain this endpoint as a validating compatibility surface for older clients, but do
      // not write anonymous users' choices to shared server storage.
      return await deps.getSettings(principal);
    } catch {
      return reply.code(503).send({ error: "settings storage is unavailable" });
    }
  });
}