import type { ExtensionAPI, ExtensionContext, Theme } from "@earendil-works/pi-coding-agent";
import { getSettingsListTheme } from "@earendil-works/pi-coding-agent";
import { Container, SettingsList, Spacer, Text, type Component } from "@earendil-works/pi-tui";
import { openAICodexProviderModels } from "../../providers/openai-codex/model-catalog.ts";
import { TextSettingSubmenu } from "./config-items-shared.ts";
import { writeContextWindowOverride } from "./context-window-store.ts";

const format = (tokens: number) => `${tokens.toLocaleString("en-US")} tokens`;

class PickerPanel extends Container {
	list?: SettingsList;
	submenuOpen = false;
	override render(width: number): string[] { return this.submenuOpen && this.list ? this.list.render(width) : super.render(width); }
	handleInput(data: string): void { this.list?.handleInput(data); }
}

export function contextWindowPicker(ctx: ExtensionContext, theme: Theme, setModel: ExtensionAPI["setModel"], waitForIdle: () => Promise<void>, close: () => void): Component {
	const catalog = openAICodexProviderModels();
	const models = ctx.modelRegistry.getAll().filter(({ provider }) => provider === "openai-codex")
		.map((model) => ctx.model?.provider === model.provider && ctx.model.id === model.id ? ctx.model : model);
	const panel = new PickerPanel();
	panel.addChild(new Text(theme.bold(theme.fg("accent", "Context windows (openai-codex)")), 2, 0));
	panel.addChild(new Spacer(1));
	panel.addChild(new Text(theme.fg("dim", "For proxy or renamed providers, edit Pi’s models.json."), 2, 0));
	panel.addChild(new Spacer(1));
	const list = new SettingsList(models.map((model) => ({
		id: model.id, label: model.name, currentValue: format(model.contextWindow),
		description: model.id,
		submenu: (_value: string, back: () => void) => {
			panel.submenuOpen = true;
			const defaultSize = catalog.find(({ id }) => id === model.id)?.contextWindow;
			const effectiveModel = () => ctx.model?.provider === model.provider && ctx.model.id === model.id
				? ctx.model : ctx.modelRegistry.find(model.provider, model.id) ?? model;
			const modelPanel = new PickerPanel();
			const summary = new Text("", 2, 0);
			const updateSummary = () => {
				const currentSize = effectiveModel().contextWindow;
				summary.setText(theme.bold(theme.fg("accent", model.name)) + `\nCurrent: ${format(currentSize)}` +
					(defaultSize && defaultSize !== currentSize ? `\nDefault: ${format(defaultSize)}` : ""));
			};
			updateSummary();
			let saving = false;
			const save = async (tokens: number | undefined) => {
				if (saving) return false;
				saving = true;
				try {
					if (ctx.modelRegistry.getError()) throw new Error("Pi reports an invalid model configuration. Fix models.json before saving.");
					writeContextWindowOverride(model.id, tokens);
					if (!ctx.isIdle()) ctx.ui.notify("Context window saved; applies when the current run settles.", "info");
					await waitForIdle();
					await ctx.modelRegistry.refresh();
					if (ctx.modelRegistry.getError()) throw new Error("Context window saved, but model configuration could not reload. Fix models.json and retry.");
					const refreshed = ctx.modelRegistry.find(model.provider, model.id);
					if (!refreshed) throw new Error("Context window saved, but the model is unavailable. Check models.json and retry.");
					if (tokens !== undefined && refreshed.contextWindow !== tokens) throw new Error("Context window saved, but another model definition takes precedence. Edit models.json and retry.");
					if (ctx.model?.provider === model.provider && ctx.model.id === model.id && !await setModel(refreshed))
						throw new Error("Context window saved, but could not apply to the active model. Sign in and retry.");
					list.updateValue(model.id, format(refreshed.contextWindow));
					updateSummary();
					ctx.ui.notify("Context window saved and applied.", "info");
					return true;
				} catch (error) {
					ctx.ui.notify(error instanceof Error ? error.message : "Could not save context window", "error");
					return false;
				} finally { saving = false; }
			};
			const presets = [272_000, 500_000, 872_000];
			modelPanel.addChild(summary);
			modelPanel.addChild(new Spacer(1));
			modelPanel.list = new SettingsList([
				...presets.map((tokens) => ({ id: String(tokens), label: format(tokens), currentValue: "", values: [""] })),
				{ id: "custom", label: "Custom", currentValue: "", submenu: (_current, finish) => {
					modelPanel.submenuOpen = true;
					const done = () => { modelPanel.submenuOpen = false; finish(); };
					let open = true;
					const input = new TextSettingSubmenu("Custom context window", "Enter a positive whole token count.", String(effectiveModel().contextWindow), async (value) => {
						if (!/^[0-9]+$/.test(value.trim()) || !Number.isSafeInteger(Number(value)) || Number(value) <= 0) {
							ctx.ui.notify("Enter a positive whole token count.", "error"); return;
						}
						if (await save(Number(value)) && open) { open = false; done(); }
					}, () => { open = false; done(); }, theme);
					input.focused = true;
					return input;
				} },
				{ id: "reset", label: "Reset to default", currentValue: "", values: [""] },
			], 6, getSettingsListTheme(), (id) => {
				void save(id === "reset" ? undefined : Number(id));
				modelPanel.list?.updateValue(id, "");
			}, () => { panel.submenuOpen = false; back(); });
			modelPanel.addChild(modelPanel.list);
			return modelPanel;
		},
	})), 8, getSettingsListTheme(), () => {}, close);
	panel.list = list;
	panel.addChild(list);
	return panel;
}