/**
 * model-picker.ts — Interactive model selection dialog.
 *
 * Presents all available models from ~/.pi/agent/models.json as a selectable list,
 * grouped by provider with context window and reasoning capability indicators.
 */
import type { ExtensionCommandContext } from "@mariozechner/pi-coding-agent";
import { getModelPickerSections } from "../model-resolver.js";

/**
 * Show model picker dialog.
 * Returns "provider/modelId" string, "inherit", or undefined if cancelled.
 */
export async function showModelPicker(
  ctx: ExtensionCommandContext,
  initialModel?: string,
): Promise<string | undefined> {
  const sections = getModelPickerSections();
  if (sections.length === 0) {
    // No models available at all — just offer inherit and custom
    const choice = await ctx.ui.select("Select model", [
      "Inherit from parent",
      "Custom... (type provider/modelId)",
    ]);
    if (!choice) return undefined;
    if (choice.startsWith("Inherit")) return "inherit";
    return promptCustomModel(ctx);
  }

  // Build a flat options list with non-selectable separators between sections
  const options: string[] = [];
  const valueMap = new Map<string, string>(); // display label → stored value

  for (const section of sections) {
    if (section.label) {
      // Section header (non-selectable)
      options.push(`─── ${section.label} ───`);
    }
    for (const item of section.models) {
      const desc = item.description ? ` — ${item.description}` : "";
      const label = `  ${item.label}${desc}`;
      options.push(label);
      valueMap.set(label, item.value);
    }
  }

  const choice = await ctx.ui.select("Select model", options);
  if (!choice) return undefined;

  const value = valueMap.get(choice);
  if (!value) return undefined; // selected a header or unknown

  if (value === "__custom__") {
    return promptCustomModel(ctx);
  }

  return value;
}

/**
 * Prompt the user to type a provider/modelId manually.
 */
async function promptCustomModel(
  ctx: ExtensionCommandContext,
): Promise<string | undefined> {
  const custom = await ctx.ui.input(
    'Custom model (e.g. "anthropic/claude-sonnet-4-20250514")',
    "",
  );
  if (!custom) return undefined;
  const trimmed = custom.trim();
  if (!trimmed) return undefined;

  // If just a model name without provider, store as-is;
  // actual provider resolution happens later via resolveModel()
  if (!trimmed.includes("/") && trimmed !== "inherit") {
    return trimmed;
  }
  return trimmed;
}