using DeepDrftManager.Services;
using DeepDrftModels.DTOs;
using DeepDrftModels.Enums;
using Microsoft.AspNetCore.Components;
using MudBlazor;

namespace DeepDrftManager.Components.Pages.Tracks;

/// <summary>
/// Shared fetch + state logic for the per-medium browsers (Cuts, Sessions, Mixes). Each subclass feeds
/// the rich <c>CmsAlbumBrowser</c> grid a medium-filtered release list, so the per-medium tabs gain the
/// same expand-tracks / delete / Type-chip / edit behaviour as the ALL tab without re-implementing any of
/// it (§8.C parity — reuse, don't fork). This base owns the loading flag, the medium-filtered load, the
/// per-release row projection, and a cover-thumbnail helper; subclasses supply the <see cref="Medium"/>,
/// an error noun, and their bespoke per-row action (Session hero upload, Mix waveform generate) via the
/// rich grid's <c>SpecialColumns</c> column model, looking their action-state row up with <see cref="RowFor"/>.
/// </summary>
/// <typeparam name="TRow">The subclass's row model wrapping a <see cref="ReleaseDto"/> plus its
/// medium-specific action state (upload/generate flags). The rich grid renders from the bare
/// <see cref="Releases"/> projection; <typeparamref name="TRow"/> only carries the action state.</typeparam>
public abstract class CmsMediumBrowserBase<TRow> : ComponentBase where TRow : class
{
    [Inject] public required ICmsReleaseService CmsReleaseService { get; set; }
    [Inject] public required ISnackbar Snackbar { get; set; }

    /// <summary>The medium this browser lists. Subclass-supplied constant.</summary>
    protected abstract ReleaseMedium Medium { get; }

    /// <summary>Plural noun for this medium used in error text (e.g. "sessions", "mixes").</summary>
    protected abstract string MediumNoun { get; }

    /// <summary>Projects a fetched release into the subclass's row model.</summary>
    protected abstract TRow ToRow(ReleaseDto release);

    /// <summary>The release carried by a subclass row, for keying the action-state lookup.</summary>
    protected abstract ReleaseDto ReleaseOf(TRow row);

    protected List<TRow> Rows { get; private set; } = new();
    protected bool Loading { get; private set; } = true;

    // Bare release projection handed to the rich grid. The grid does the expand/delete/edit/Type-chip;
    // it never sees TRow. Rebuilt on every (re)load so the grid re-projects against a fresh reference.
    protected IReadOnlyList<ReleaseDto> Releases { get; private set; } = Array.Empty<ReleaseDto>();

    // release.Id → action-state row, so a SpecialColumns cell delegate (which the grid hands a ReleaseDto)
    // can recover its TRow. Rebuilt alongside Rows so a refresh never leaves a stale row behind.
    private Dictionary<long, TRow> _rowsById = new();

    protected override async Task OnInitializedAsync() => await LoadAsync();

    /// <summary>Recovers the action-state row for a release the rich grid is rendering. Null if the
    /// release is not in the current page (e.g. just deleted), in which case the action is skipped.</summary>
    protected TRow? RowFor(ReleaseDto release) =>
        _rowsById.TryGetValue(release.Id, out var row) ? row : null;

    /// <summary>
    /// Reloads the medium-filtered release list. Wired to the rich grid's <c>OnReleasesChanged</c> so a
    /// delete re-fetches the authoritative list (track counts, orphan cleanup) — the same single-load
    /// posture <c>CmsAllReleasesGrid</c> uses for the ALL tab.
    /// </summary>
    protected async Task ReloadAsync()
    {
        await LoadAsync();
        StateHasChanged();
    }

    private async Task LoadAsync()
    {
        Loading = true;
        // Single-track releases; a single generous page covers the CMS catalogue (same small-catalogue
        // assumption the album browser makes).
        var result = await CmsReleaseService.GetPagedAsync(
            Medium, page: 1, pageSize: 100,
            sortColumn: "Title", sortDescending: false);

        if (result.Success && result.Value is not null)
        {
            Rows = result.Value.Items.Select(ToRow).ToList();
        }
        else
        {
            var error = result.Messages.FirstOrDefault()?.Message ?? "Unknown error";
            Snackbar.Add($"Failed to load {MediumNoun}: {error}", Severity.Error);
            Rows = new List<TRow>();
        }

        Releases = Rows.Select(ReleaseOf).ToList();
        _rowsById = Rows.ToDictionary(r => ReleaseOf(r).Id);
        Loading = false;
    }

    // Relative path — resolves against the Manager's own origin, proxied by ImageProxyController.
    protected static string ThumbUrl(string entryKey) =>
        $"/api/image/{Uri.EscapeDataString(entryKey)}";
}