import { isoToEpochMs, jsonBody, makeLimit, statusForPercent, unknownReport } from "../driver.js";
import { defineUsageFeed } from "../registry.js";
import type { UsageLimit, UsageReportBody, UsageRequest, UsageState, UsageStep } from "../types.js";

export const OPENCODE_GO_USAGE_URL = "https://opencode.ai/zen/go/v1/usage";

function asRecord(value: unknown): Record<string, unknown> | undefined {
	return value && typeof value === "object" && !Array.isArray(value) ? (value as Record<string, unknown>) : undefined;
}

function asNumber(value: unknown): number | undefined {
	if (typeof value === "number" && Number.isFinite(value)) return value;
	if (typeof value === "string" && value.trim()) {
		const parsed = Number(value);
		return Number.isFinite(parsed) ? parsed : undefined;
	}
	return undefined;
}

interface WindowDef {
	key: string;
	label: string;
	windowLabel: string;
}

const OPENCODE_WINDOWS: readonly WindowDef[] = [
	{ key: "rolling", label: "Session", windowLabel: "5h window" },
	{ key: "weekly", label: "Weekly", windowLabel: "7d window" },
	{ key: "monthly", label: "Monthly", windowLabel: "30d window" },
];

export function parseOpenCodeGoUsage(payload: unknown): { planType?: string; limits: UsageLimit[]; notes?: string[] } {
	const root = asRecord(payload);
	const usage = asRecord(root?.usage);
	if (!usage) return { limits: [] };

	const limits: UsageLimit[] = [];

	for (const win of OPENCODE_WINDOWS) {
		const rawWindow = asRecord(usage[win.key]);
		if (!rawWindow) continue;

		// Converted from: percentage (0..100)
		const usedPercent = asNumber(rawWindow.percent);
		// Converted from: ISO-8601 string (e.g. "2026-09-16T04:40:14.037Z")
		const resetsAt = isoToEpochMs(rawWindow.resetsAt);

		const rawStatus = typeof rawWindow.status === "string" ? rawWindow.status.toLowerCase() : undefined;
		const isRateLimited = rawStatus === "rate-limited" || rawStatus === "exhausted";
		const status =
			isRateLimited || (usedPercent !== undefined && usedPercent >= 100)
				? "exhausted"
				: statusForPercent(usedPercent);

		limits.push(
			makeLimit(win.label, usedPercent, {
				windowLabel: win.windowLabel,
				resetsAt,
				status,
			}),
		);
	}

	return {
		planType: "Go",
		limits,
		notes: ["OpenCode Go unified models"],
	};
}

export const opencodegoUsageFeed = defineUsageFeed({
	provider: "opencode-go",
	providerName: "OpenCode Zen",
	credentialKinds: ["apiKey"],
	advance(state: UsageState, responses): UsageStep {
		const credential = state.credential;
		if (credential.kind !== "apiKey") return { report: unknownReport("opencode-go needs an apiKey credential") };

		if (responses.length === 0) {
			const headers = {
				Authorization: `Bearer ${credential.apiKey}`,
				Accept: "application/json",
				"User-Agent": "OpenCode-Status-Plugin/1.0",
			};
			const requests: UsageRequest[] = [{ kind: "http", method: "GET", url: OPENCODE_GO_USAGE_URL, headers }];
			return { requests };
		}

		const response = responses[0];
		if (!response || response.status !== 200)
			return { report: unknownReport(`HTTP ${response?.status ?? "no response"}`) };
		const payload = jsonBody(response);
		if (payload === undefined) return { report: unknownReport("usage body is not JSON") };

		const parsed = parseOpenCodeGoUsage(payload);
		const body: UsageReportBody = {
			...parsed,
			accountId: credential.accountId,
			email: credential.email,
			error: null,
		};
		return { report: body };
	},
});