using System.Net;
using System.Net.Http.Json;
using System.Text;
using LudosData.Api.Contracts;

namespace LudosData.Api.Tests;

public class LibraryTests(LudosApiFactory factory) : IClassFixture<LudosApiFactory>
{
    private static async Task SeedAsync(HttpClient client)
    {
        await client.PostAsJsonAsync("/api/games", new
        {
            title = "Chrono Trigger",
            system = "SNES",
            genre = "rpg",
            year = "1995",
            developer = "Square",
            own = true,
            played = true,
            finished = true,
        });
        await client.PostAsJsonAsync("/api/games", new
        {
            title = "Ico",
            system = "PS2",
            genre = "adventure",
            year = "2001",
            own = true,
        });
    }

    private static MultipartFormDataContent FileContent(string body, string name, string mediaType)
    {
        var content = new MultipartFormDataContent();
        var part = new ByteArrayContent(Encoding.UTF8.GetBytes(body));
        part.Headers.ContentType = new System.Net.Http.Headers.MediaTypeHeaderValue(mediaType);
        content.Add(part, "file", name);
        return content;
    }

    // ---- export ----------------------------------------------------------

    [Fact]
    public async Task Json_export_contains_the_library()
    {
        var client = await factory.CreateUserClientAsync("exp-json");
        await SeedAsync(client);

        var response = await client.GetAsync("/api/library/export?format=json");
        response.EnsureSuccessStatusCode();

        Assert.Equal("application/json", response.Content.Headers.ContentType?.MediaType);
        Assert.Contains("attachment", response.Content.Headers.ContentDisposition?.DispositionType
            ?? response.Content.Headers.ContentDisposition?.ToString() ?? "attachment");

        var payload = await response.Content.ReadFromJsonAsync<LibraryExport>();
        Assert.Equal(2, payload!.Count);
        Assert.Contains(payload.Games, g => g.Title == "Chrono Trigger" && g.Developer == "Square");
    }

    [Fact]
    public async Task Csv_export_has_a_header_and_one_row_per_game()
    {
        var client = await factory.CreateUserClientAsync("exp-csv");
        await SeedAsync(client);

        var csv = await client.GetStringAsync("/api/library/export?format=csv");
        var rows = LudosData.Api.Services.Csv.Parse(csv.TrimStart(''));

        Assert.Equal("title", rows[0][0]);
        Assert.Equal(3, rows.Count); // header + 2 games
        Assert.Contains(rows.Skip(1), r => r[0] == "Chrono Trigger");
    }

    [Fact]
    public async Task Export_only_covers_the_signed_in_users_games()
    {
        var alice = await factory.CreateUserClientAsync("exp-alice");
        var bob = await factory.CreateUserClientAsync("exp-bob");
        await SeedAsync(alice);
        await bob.PostAsJsonAsync("/api/games", new { title = "Bob Only", system = "N64", own = true });

        var payload = await bob.GetFromJsonAsync<LibraryExport>("/api/library/export?format=json");

        Assert.Equal(1, payload!.Count);
        Assert.Equal("Bob Only", payload.Games[0].Title);
    }

    [Fact]
    public async Task Export_rejects_an_unknown_format()
    {
        var client = await factory.CreateUserClientAsync("exp-bad");

        var response = await client.GetAsync("/api/library/export?format=xml");

        Assert.Equal(HttpStatusCode.BadRequest, response.StatusCode);
    }

    [Fact]
    public async Task Export_and_import_round_trip_without_loss()
    {
        var source = await factory.CreateUserClientAsync("round-source");
        await SeedAsync(source);
        var exported = await source.GetStringAsync("/api/library/export?format=json");

        var target = await factory.CreateUserClientAsync("round-target");
        var response = await target.PostAsync("/api/library/import",
            FileContent(exported, "library.json", "application/json"));
        response.EnsureSuccessStatusCode();

        var before = await source.GetFromJsonAsync<LibraryExport>("/api/library/export?format=json");
        var after = await target.GetFromJsonAsync<LibraryExport>("/api/library/export?format=json");

        Assert.Equal(before!.Count, after!.Count);
        Assert.Equal(
            before.Games.OrderBy(g => g.Title).Select(g => (g.Title, g.System, g.Developer, g.Finished)),
            after.Games.OrderBy(g => g.Title).Select(g => (g.Title, g.System, g.Developer, g.Finished)));
    }

    // ---- import ----------------------------------------------------------

    [Fact]
    public async Task Import_creates_missing_games_and_updates_matching_ones()
    {
        var client = await factory.CreateUserClientAsync("imp-merge");
        await SeedAsync(client);

        const string csv = """
            title,system,genre,year,own,finished
            Chrono Trigger,SNES,rpg,1995,true,false
            Super Metroid,SNES,platformer,1994,true,true
            """;

        var result = await (await client.PostAsync("/api/library/import",
            FileContent(csv, "in.csv", "text/csv"))).Content.ReadFromJsonAsync<ImportResult>();

        Assert.Equal(1, result!.Created);   // Super Metroid
        Assert.Equal(1, result.Updated);    // Chrono Trigger matched on title + system
        Assert.Equal(0, result.Deleted);

        // The update took effect: it was finished before, and the file says otherwise.
        var page = await client.GetFromJsonAsync<PagePayload>("/api/games?search=Chrono");
        Assert.False(page!.Items[0].Finished);
    }

    [Fact]
    public async Task The_same_title_on_a_different_system_is_a_different_game()
    {
        var client = await factory.CreateUserClientAsync("imp-platform");
        await client.PostAsJsonAsync("/api/games", new
        {
            title = "Donkey Kong Country", system = "SNES", own = true,
        });

        const string csv = """
            title,system,own
            Donkey Kong Country,SNES,true
            Donkey Kong Country,GB,true
            Donkey Kong Country,GBA,true
            """;

        var result = await (await client.PostAsync("/api/library/import",
            FileContent(csv, "in.csv", "text/csv"))).Content.ReadFromJsonAsync<ImportResult>();

        Assert.Equal(2, result!.Created);  // GB and GBA
        Assert.Equal(1, result.Updated);   // the existing SNES row
    }

    [Fact]
    public async Task Dry_run_reports_what_would_happen_and_changes_nothing()
    {
        var client = await factory.CreateUserClientAsync("imp-dry");
        await SeedAsync(client);

        const string csv = """
            title,system,own
            Brand New Game,N64,true
            """;

        var result = await (await client.PostAsync("/api/library/import?dryRun=true",
            FileContent(csv, "in.csv", "text/csv"))).Content.ReadFromJsonAsync<ImportResult>();

        Assert.True(result!.DryRun);
        Assert.Equal(1, result.Created);

        var page = await client.GetFromJsonAsync<PagePayload>("/api/games");
        Assert.Equal(2, page!.Total); // still just the seeded pair
    }

    [Fact]
    public async Task Replace_mode_clears_the_library_first()
    {
        var client = await factory.CreateUserClientAsync("imp-replace");
        await SeedAsync(client);

        const string csv = """
            title,system,own
            Only Survivor,GC,true
            """;

        var result = await (await client.PostAsync("/api/library/import?mode=Replace",
            FileContent(csv, "in.csv", "text/csv"))).Content.ReadFromJsonAsync<ImportResult>();

        Assert.Equal(2, result!.Deleted);
        Assert.Equal(1, result.Created);

        var page = await client.GetFromJsonAsync<PagePayload>("/api/games");
        Assert.Equal(1, page!.Total);
        Assert.Equal("Only Survivor", page.Items[0].Title);
    }

    [Fact]
    public async Task Import_never_touches_another_users_library()
    {
        var alice = await factory.CreateUserClientAsync("imp-alice");
        var bob = await factory.CreateUserClientAsync("imp-bob");
        await SeedAsync(alice);
        await SeedAsync(bob);

        // Replace is the most destructive mode; it must stop at the caller.
        await bob.PostAsync("/api/library/import?mode=Replace",
            FileContent("title,system,own\nBob Only,GC,true", "in.csv", "text/csv"));

        var alicePage = await alice.GetFromJsonAsync<PagePayload>("/api/games");
        Assert.Equal(2, alicePage!.Total);
    }

    [Fact]
    public async Task Rows_without_a_title_are_reported_rather_than_imported()
    {
        var client = await factory.CreateUserClientAsync("imp-invalid");

        const string csv = """
            title,system,own
            ,SNES,true
            Valid Game,SNES,true
            """;

        var result = await (await client.PostAsync("/api/library/import",
            FileContent(csv, "in.csv", "text/csv"))).Content.ReadFromJsonAsync<ImportResult>();

        Assert.Equal(1, result!.Created);
        Assert.Single(result.Errors);
        Assert.Equal(2, result.Errors[0].Row); // header is row 1
    }

    [Fact]
    public async Task Csv_survives_commas_quotes_and_newlines_in_a_description()
    {
        var client = await factory.CreateUserClientAsync("imp-quoting");
        var awkward = "A description with, a comma, \"quotes\" and\na newline.";

        await client.PostAsJsonAsync("/api/games", new
        {
            title = "Awkward, Game \"Title\"",
            system = "PS1",
            description = awkward,
            own = true,
        });

        // Round-trip through CSV rather than asserting on the encoding itself.
        var csv = await client.GetStringAsync("/api/library/export?format=csv");

        var target = await factory.CreateUserClientAsync("imp-quoting-target");
        await target.PostAsync("/api/library/import", FileContent(csv, "in.csv", "text/csv"));

        var payload = await target.GetFromJsonAsync<LibraryExport>("/api/library/export?format=json");
        var game = Assert.Single(payload!.Games);

        Assert.Equal("Awkward, Game \"Title\"", game.Title);
        Assert.Equal(awkward, game.Description);
    }

    [Fact]
    public async Task A_bare_json_array_is_accepted_as_well_as_the_envelope()
    {
        var client = await factory.CreateUserClientAsync("imp-bare");

        const string json = """
            [ { "title": "Bare Array Game", "system": "N64", "own": true } ]
            """;

        var result = await (await client.PostAsync("/api/library/import",
            FileContent(json, "in.json", "application/json"))).Content.ReadFromJsonAsync<ImportResult>();

        Assert.Equal(1, result!.Created);
    }

    [Fact]
    public async Task Malformed_files_are_rejected_with_a_reason()
    {
        var client = await factory.CreateUserClientAsync("imp-malformed");

        var badJson = await client.PostAsync("/api/library/import",
            FileContent("{ not valid json", "in.json", "application/json"));
        var headerless = await client.PostAsync("/api/library/import",
            FileContent("name,platform\nFoo,SNES", "in.csv", "text/csv"));
        var empty = await client.PostAsync("/api/library/import",
            FileContent("", "in.csv", "text/csv"));

        Assert.Equal(HttpStatusCode.BadRequest, badJson.StatusCode);
        Assert.Equal(HttpStatusCode.BadRequest, headerless.StatusCode);
        Assert.Equal(HttpStatusCode.BadRequest, empty.StatusCode);
    }

    [Fact]
    public async Task Export_and_import_require_a_token()
    {
        var anonymous = factory.CreateClient();

        Assert.Equal(HttpStatusCode.Unauthorized,
            (await anonymous.GetAsync("/api/library/export")).StatusCode);
        Assert.Equal(HttpStatusCode.Unauthorized,
            (await anonymous.PostAsync("/api/library/import",
                FileContent("title\nX", "in.csv", "text/csv"))).StatusCode);
    }

    private record GamePayload(int Id, string Title, bool Finished);
    private record PagePayload(List<GamePayload> Items, int Total);
}