using BoardApp.Config;

namespace BoardApp.Services;

public sealed class ScenarioService
{
    private readonly BoardConfigLoader _cfg;

    public ScenarioService(BoardConfigLoader cfg)
    {
        _cfg = cfg;
    }

    public sealed record HomeScenario(string Id, string Name, string Image);
    public sealed record HomeCategory(string Id, string Name, List<HomeScenario> Scenarios);

    public enum ScenarioSource
    {
        System,
        User
    }

    public static string ToScenarioKey(ScenarioSource source, string scenarioId)
        => (source == ScenarioSource.System ? "s:" : "u:") + scenarioId;

    public sealed record ScenarioKeyParts(ScenarioSource Source, string ScenarioId);

    public static ScenarioKeyParts ParseScenarioKey(string input)
    {
        var raw = (input ?? "").Trim();
        if (raw.StartsWith("s:")) return new ScenarioKeyParts(ScenarioSource.System, raw[2..]);
        if (raw.StartsWith("u:")) return new ScenarioKeyParts(ScenarioSource.User, raw[2..]);
        return new ScenarioKeyParts(ScenarioSource.System, raw);
    }

    private Dictionary<string, PageDef> PageMap()
    {
        var cfg = _cfg.LoadPagesConfig();
        var map = new Dictionary<string, PageDef>(StringComparer.Ordinal);
        foreach (var p in cfg.Pages)
        {
            map[p.Id] = p;
        }
        return map;
    }

    public List<HomeCategory> LoadHomeCatalogForUser(string username)
    {
        var pagesById = PageMap();
        var sys = _cfg.LoadSystemScenariosConfig();
        var users = _cfg.LoadUserScenariosConfig();
        users.Users.TryGetValue(username, out var u);
        var userScenarios = u?.Scenarios ?? new List<UserScenario>();

        var sysCats = sys.Categories.Select(c => new HomeCategory(
            c.Id,
            c.Name,
            (c.Scenarios ?? new List<SystemScenario>())
                .Select(s => new HomeScenario(ToScenarioKey(ScenarioSource.System, s.Id), s.Name, s.Image))
                .ToList()
        )).ToList();

        var my = new HomeCategory(
            "my",
            "我的场景",
            userScenarios.Select(s =>
            {
                var img = s.Image;
                if (string.IsNullOrWhiteSpace(img))
                {
                    var first = s.Pages.FirstOrDefault();
                    if (first is not null && pagesById.TryGetValue(first.PageId, out var pd))
                    {
                        img = pd.Image;
                    }
                }
                return new HomeScenario(ToScenarioKey(ScenarioSource.User, s.Id), s.Name, img ?? "");
            }).ToList()
        );

        return my.Scenarios.Count > 0 ? new List<HomeCategory> { my }.Concat(sysCats).ToList() : sysCats;
    }

    public Dictionary<string, string> BuildScenarioImageMapForUser(string username)
    {
        var map = new Dictionary<string, string>(StringComparer.Ordinal);
        var cats = LoadHomeCatalogForUser(username);
        foreach (var c in cats)
        {
            foreach (var s in c.Scenarios)
            {
                map[s.Id] = s.Image;
            }
        }
        return map;
    }

    public sealed record ScenarioPage(string Id, string Title, string BoardUrl, int Staytime);
    public sealed record Scenario(string Id, string Name, string Image, List<ScenarioPage> Pages);

    public sealed record ResolvedScenario(ScenarioSource Source, Scenario Scenario);

    private static List<ScenarioPage> ExpandPages(IEnumerable<ScenarioPageRef> refs, Dictionary<string, PageDef> pagesById)
    {
        var list = new List<ScenarioPage>();
        foreach (var r in refs)
        {
            if (r is null) continue;
            if (!pagesById.TryGetValue(r.PageId, out var def)) continue;
            list.Add(new ScenarioPage(def.Id, def.Title, def.BoardUrl, r.Staytime));
        }
        return list;
    }

    public ResolvedScenario? ResolveScenarioForUser(string username, string scenarioKey)
    {
        var pagesById = PageMap();
        var key = ParseScenarioKey(scenarioKey);

        if (key.Source == ScenarioSource.System)
        {
            var sys = _cfg.LoadSystemScenariosConfig();
            foreach (var cat in sys.Categories)
            {
                foreach (var sc in cat.Scenarios)
                {
                    if (!string.Equals(sc.Id, key.ScenarioId, StringComparison.Ordinal)) continue;
                    var pages = ExpandPages(sc.Pages, pagesById);
                    return new ResolvedScenario(
                        ScenarioSource.System,
                        new Scenario(ToScenarioKey(ScenarioSource.System, sc.Id), sc.Name, sc.Image, pages)
                    );
                }
            }
            return null;
        }

        var users = _cfg.LoadUserScenariosConfig();
        if (!users.Users.TryGetValue(username, out var u)) return null;
        var mine = u.Scenarios ?? new List<UserScenario>();
        var usc = mine.FirstOrDefault(x => string.Equals(x.Id, key.ScenarioId, StringComparison.Ordinal));
        if (usc is null) return null;
        var upages = ExpandPages(usc.Pages, pagesById);
        return new ResolvedScenario(
            ScenarioSource.User,
            new Scenario(ToScenarioKey(ScenarioSource.User, usc.Id), usc.Name, usc.Image, upages)
        );
    }
}