using interfaces;
using Microsoft.Extensions.Options;
using options;

namespace services;

internal class SmappeeTokenService : IBearerTokenService
{
    private readonly ChargerOptions options;
    private readonly IHttpClientFactory httpClientFactory;

    private TokenData? tokenData = null;

    public SmappeeTokenService(
        IOptions<ChargerOptions> options,
        IHttpClientFactory httpClientFactory
    )
    {
        this.options = options?.Value ?? throw new ArgumentNullException(nameof(options));
        this.httpClientFactory =
            httpClientFactory ?? throw new ArgumentNullException(nameof(httpClientFactory));
    }

    public async ValueTask<string> GetToken(bool forceNewToken)
    {
        if (
            tokenData == null
            || tokenData.Expiration < DateTime.UtcNow.AddSeconds(-10)
            || forceNewToken
        )
        {
            tokenData = await RequestNewToken();
        }
        return tokenData.Token;
    }

    private async Task<TokenData> RequestNewToken()
    {
        var httpClient = httpClientFactory.CreateClient("smappeeTokenService");
        httpClient.BaseAddress = options.Url;

        var result = await httpClient.PostAsync(
            "/dev/v3/oauth2/token",
            new FormUrlEncodedContent(
                new Dictionary<string, string>
                {
                    ["grant_type"] = "password",
                    ["client_id"] = options.ClientId,
                    ["client_secret"] = options.ClientSecret,
                    ["username"] = options.UserName,
                    ["password"] = options.Password,
                }
            )
        );
        result.EnsureSuccessStatusCode();
        var tokenResponse =
            await result.Content.ReadFromJsonAsync<TokenResponse>()
            ?? throw new InvalidOperationException("Token could not be fetched");
        return new TokenData(
            tokenResponse.access_token,
            DateTime.UtcNow.AddSeconds(tokenResponse.expires_in)
        );
    }

    record TokenResponse(string access_token, int expires_in);

    record TokenData(string Token, DateTime Expiration);
}