@page "/admin/connectors"
@inject Microsoft.EntityFrameworkCore.IDbContextFactory<MeterVault.Infrastructure.Persistence.MeterVaultDbContext> DbFactory
@inject MeterVault.Infrastructure.Ingestion.HaConnectionTester HaTester
@inject MeterVault.Infrastructure.Security.SecretProtector Secrets
@inject ISnackbar Snackbar
@inject IDialogService DialogService
@using Microsoft.EntityFrameworkCore
@using MeterVault.Infrastructure.Ingestion
@using MudBlazor

<PageTitle>MeterVault — Connectors</PageTitle>

<div class="d-flex align-center justify-space-between mb-4 flex-wrap" style="gap:1rem">
    <MudText Typo="Typo.h4">Connectors</MudText>
    <MudButton Variant="Variant.Filled" Color="Color.Primary" StartIcon="@Icons.Material.Filled.Add" OnClick="@(() => OpenEdit(null))">
        Add connector
    </MudButton>
</div>

<MudAlert Severity="Severity.Info" Class="mb-4" Dense="true">
    Secrets are never stored here. Credentials/tokens are referenced by the <b>name of an environment variable</b>
    (or Docker secret) resolved at runtime.
</MudAlert>

@if (_endpoints is null)
{
    <MudProgressLinear Indeterminate="true" Color="Color.Primary" />
}
else
{
    <MudTable Items="_endpoints" Dense="true" Hover="true" Elevation="2">
        <HeaderContent>
            <MudTh>Name</MudTh>
            <MudTh>Type</MudTh>
            <MudTh>Enabled</MudTh>
            <MudTh>Last status</MudTh>
            <MudTh>Last seen</MudTh>
            <MudTh Style="text-align:right">Actions</MudTh>
        </HeaderContent>
        <RowTemplate>
            <MudTd DataLabel="Name">@context.Name</MudTd>
            <MudTd DataLabel="Type">@context.Type</MudTd>
            <MudTd DataLabel="Enabled">@(context.IsEnabled ? "yes" : "no")</MudTd>
            <MudTd DataLabel="Last status">@(context.LastStatus ?? "—")</MudTd>
            <MudTd DataLabel="Last seen">@(context.LastSeenAt?.ToString("yyyy-MM-dd HH:mm") ?? "—")</MudTd>
            <MudTd DataLabel="Actions" Style="text-align:right">
                <MudIconButton Icon="@Icons.Material.Filled.Edit" Size="Size.Small" OnClick="@(() => OpenEdit(context))" />
                <MudIconButton Icon="@Icons.Material.Filled.Delete" Size="Size.Small" Color="Color.Error" OnClick="@(() => DeleteAsync(context))" />
            </MudTd>
        </RowTemplate>
    </MudTable>
    @if (_endpoints.Count == 0)
    {
        <MudAlert Severity="Severity.Normal" Class="mt-4">No connectors yet. Add an MQTT broker or a Home Assistant connection.</MudAlert>
    }
}

<MudDialog @bind-Visible="_editOpen" Options="_dialogOptions">
    <TitleContent>
        <MudText Typo="Typo.h6">@(_working.Id == 0 ? "New connector" : $"Edit {_working.Name}")</MudText>
    </TitleContent>
    <DialogContent>
        <MudSelect T="EndpointType" @bind-Value="_working.Type" Label="Type" Class="mb-2">
            @foreach (var type in Enum.GetValues<EndpointType>())
            {
                <MudSelectItem T="EndpointType" Value="type">@type</MudSelectItem>
            }
        </MudSelect>
        <MudTextField @bind-Value="_working.Name" Label="Name" Required="true" Class="mb-2" />

        @if (_working.Type == EndpointType.HomeAssistant)
        {
            <MudTextField @bind-Value="_working.BaseUrl" Label="Base URL (e.g. http://homeassistant.local:8123)" Class="mb-2" />
            <MudSwitch T="bool" @bind-Value="_working.UseDirectToken" Label="Enter the token here" Color="Color.Primary" Class="mb-1" />
            @if (_working.UseDirectToken)
            {
                <MudTextField @bind-Value="_working.Token" InputType="InputType.Password" Class="mb-1"
                              Label="@(_working.HasStoredToken ? "Long-lived access token (stored — type to replace)" : "Long-lived access token")" />
                <MudText Typo="Typo.caption" Color="Color.Secondary" Class="mb-2 d-block">
                    Encrypted before it is stored; database dumps and JSON exports carry nothing usable.
                </MudText>
            }
            else
            {
                <MudTextField @bind-Value="_working.TokenEnv" Label="Token env-var name (e.g. HA_TOKEN)" Class="mb-1" />
                <MudText Typo="Typo.caption" Color="Color.Secondary" Class="mb-2 d-block">
                    The variable's <em>name</em>, not the token. Set it on the server and restart the app.
                </MudText>
            }
            <MudSwitch T="bool" @bind-Value="_working.UseWebSocket" Label="Real-time WebSocket push" Color="Color.Primary" Class="mb-1" />
            <MudText Typo="Typo.caption" Color="Color.Secondary" Class="mb-2 d-block">
                On: subscribe to state changes and ingest in real time. Off: REST poll on each source's interval.
            </MudText>
            <MudTextField @bind-Value="_working.TestEntityId" Label="Test entity id (optional, e.g. sensor.house_power)" Class="mb-2" />
            <MudButton Variant="Variant.Outlined" StartIcon="@Icons.Material.Filled.NetworkCheck" OnClick="TestHaAsync" Disabled="_testing" Class="mb-2">
                Test connection
            </MudButton>
            @if (_testing)
            {
                <MudProgressLinear Indeterminate="true" Color="Color.Primary" Class="mb-2" />
            }
            @if (_testResult is not null)
            {
                <MudAlert Severity="@(_testResult.Ok ? Severity.Success : Severity.Error)" Dense="true" Class="mb-2">@_testResult.Message</MudAlert>
            }
        }
        else
        {
            <MudTextField @bind-Value="_working.Host" Label="Host" Class="mb-2" />
            <MudNumericField T="int" @bind-Value="_working.Port" Label="Port" Class="mb-2" />
            <MudSwitch T="bool" @bind-Value="_working.Tls" Label="TLS" Color="Color.Primary" Class="mb-2" />
            <MudSwitch T="bool" @bind-Value="_working.UseDirectCredentials" Label="Enter credentials here" Color="Color.Primary" Class="mb-1" />
            @if (_working.UseDirectCredentials)
            {
                <MudTextField @bind-Value="_working.Username" Label="Username (optional)" Class="mb-1" />
                <MudTextField @bind-Value="_working.Password" InputType="InputType.Password" Class="mb-1"
                              Label="@(_working.HasStoredPassword ? "Password (stored — type to replace)" : "Password (optional)")" />
                <MudText Typo="Typo.caption" Color="Color.Secondary" Class="mb-2 d-block">
                    Encrypted before it is stored; database dumps and JSON exports carry nothing usable.
                </MudText>
            }
            else
            {
                <MudTextField @bind-Value="_working.UsernameEnv" Label="Username env-var name (optional)" Class="mb-2" />
                <MudTextField @bind-Value="_working.PasswordEnv" Label="Password env-var name (optional)" Class="mb-2" />
            }
            <MudTextField @bind-Value="_working.ExtraTopics" Label="Extra topics (comma-separated, optional)" Class="mb-2" />
        }
        <MudSwitch T="bool" @bind-Value="_working.IsEnabled" Label="Enabled" Color="Color.Primary" />
    </DialogContent>
    <DialogActions>
        <MudButton OnClick="@(() => _editOpen = false)">Cancel</MudButton>
        <MudButton Color="Color.Primary" Variant="Variant.Filled" OnClick="SaveAsync">Save</MudButton>
    </DialogActions>
</MudDialog>

@code {
    private List<IngestionEndpoint>? _endpoints;
    private bool _editOpen;
    private bool _testing;
    private HaTestResult? _testResult;
    private EditModel _working = new();
    private readonly DialogOptions _dialogOptions = new() { MaxWidth = MaxWidth.Small, FullWidth = true };

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

    private async Task LoadAsync()
    {
        await using var db = await DbFactory.CreateDbContextAsync();
        _endpoints = await db.IngestionEndpoints.AsNoTracking().OrderBy(e => e.Name).ToListAsync();
    }

    private void OpenEdit(IngestionEndpoint? endpoint)
    {
        _testResult = null;
        if (endpoint is null)
        {
            _working = new EditModel();
        }
        else if (endpoint.Type == EndpointType.HomeAssistant)
        {
            var ha = HaEndpointConfig.Parse(endpoint.Config);
            _working = new EditModel
            {
                Id = endpoint.Id, Type = endpoint.Type, Name = endpoint.Name, IsEnabled = endpoint.IsEnabled,
                BaseUrl = ha.BaseUrl, TokenEnv = ha.TokenEnv, UseWebSocket = ha.UseWebSocket,
                // Carry the ciphertext through untouched and never send the secret to the browser:
                // the field stays blank and only a typed value replaces what is stored.
                TokenEnc = ha.TokenEnc,
                UseDirectToken = !string.IsNullOrWhiteSpace(ha.TokenEnc),
                // The host the stored token was saved against; a stored token is never sent anywhere else.
                SavedBaseUrl = ha.BaseUrl,
            };
        }
        else
        {
            var mqtt = EndpointConfig.Parse(endpoint.Config);
            _working = new EditModel
            {
                Id = endpoint.Id, Type = endpoint.Type, Name = endpoint.Name, IsEnabled = endpoint.IsEnabled,
                Host = mqtt.Host, Port = mqtt.Port, Tls = mqtt.Tls,
                UsernameEnv = mqtt.UsernameEnv, PasswordEnv = mqtt.PasswordEnv,
                Username = mqtt.Username, PasswordEnc = mqtt.PasswordEnc,
                UseDirectCredentials =
                    !string.IsNullOrWhiteSpace(mqtt.Username) || !string.IsNullOrWhiteSpace(mqtt.PasswordEnc),
                ExtraTopics = string.Join(", ", mqtt.ExtraTopics),
            };
        }
        _editOpen = true;
    }

    private async Task TestHaAsync()
    {
        _testing = true;
        _testResult = null;
        try
        {
            // Test what the connector would actually use — including a token typed but not yet
            // saved, so a bad token is caught before it is stored.
            if (_working.UseDirectToken)
            {
                if (!string.IsNullOrWhiteSpace(_working.Token))
                {
                    _testResult = await HaTester.TestAsync(_working.BaseUrl, _working.Token, _working.TestEntityId);
                }
                else if (!SameOrigin(_working.BaseUrl, _working.SavedBaseUrl))
                {
                    // Storing the token encrypted means the UI can decrypt something the operator
                    // can no longer read. Sending it to a Base URL edited in this dialog would turn
                    // "Test connection" into an exfiltration primitive — point it at any host and the
                    // token arrives as a Bearer header. A stored secret only ever goes to the origin
                    // it was saved for; testing elsewhere means typing the token again.
                    _testResult = new HaTestResult(false,
                        "Base URL differs from the saved one. Re-enter the token to test against a different host — "
                        + "a stored token is only sent to the host it was saved for.");
                }
                else if (Secrets.TryUnprotect(_working.TokenEnc, out var stored) && stored is { Length: > 0 })
                {
                    _testResult = await HaTester.TestAsync(_working.BaseUrl, stored, _working.TestEntityId);
                }
                else
                {
                    _testResult = new HaTestResult(false, "Enter a token first.");
                }
            }
            else if (string.IsNullOrWhiteSpace(_working.TokenEnv))
            {
                _testResult = new HaTestResult(false,
                    "Name the environment variable holding the token, or switch on \"Enter the token here\".");
            }
            else if (Environment.GetEnvironmentVariable(_working.TokenEnv) is not { Length: > 0 } envToken)
            {
                _testResult = new HaTestResult(false,
                    $"Environment variable '{_working.TokenEnv}' is not set on the server. Set it and restart the app, "
                    + "or switch on \"Enter the token here\" to store the token directly.");
            }
            else
            {
                _testResult = await HaTester.TestAsync(_working.BaseUrl, envToken, _working.TestEntityId);
            }
        }
        finally
        {
            _testing = false;
        }
    }

    private async Task SaveAsync()
    {
        if (string.IsNullOrWhiteSpace(_working.Name))
        {
            Snackbar.Add("Name is required.", Severity.Warning);
            return;
        }

        if (_working.Type == EndpointType.HomeAssistant
            && _working.UseDirectToken
            && string.IsNullOrWhiteSpace(_working.Token)
            && !_working.HasStoredToken)
        {
            Snackbar.Add("Enter the token, or switch off \"Enter the token here\" and name an env var.", Severity.Warning);
            return;
        }

        var config = _working.Type == EndpointType.HomeAssistant
            ? new HaEndpointConfig
            {
                BaseUrl = Trim(_working.BaseUrl),
                UseWebSocket = _working.UseWebSocket,
                // Exactly one storage form survives a save: switching modes clears the other, so a
                // stale token cannot linger and silently win at resolution time.
                TokenEnv = _working.UseDirectToken ? null : Trim(_working.TokenEnv),
                TokenEnc = _working.UseDirectToken ? ProtectOrKeep(_working.Token, _working.TokenEnc) : null,
            }.ToJson()
            : new EndpointConfig
            {
                Host = string.IsNullOrWhiteSpace(_working.Host) ? "localhost" : _working.Host.Trim(),
                Port = _working.Port,
                Tls = _working.Tls,
                UsernameEnv = _working.UseDirectCredentials ? null : Trim(_working.UsernameEnv),
                PasswordEnv = _working.UseDirectCredentials ? null : Trim(_working.PasswordEnv),
                Username = _working.UseDirectCredentials ? Trim(_working.Username) : null,
                PasswordEnc = _working.UseDirectCredentials
                    ? ProtectOrKeep(_working.Password, _working.PasswordEnc)
                    : null,
                ExtraTopics = SplitTopics(_working.ExtraTopics),
            }.ToJson();

        await using var db = await DbFactory.CreateDbContextAsync();
        if (_working.Id == 0)
        {
            db.IngestionEndpoints.Add(new IngestionEndpoint
            {
                Type = _working.Type, Name = _working.Name.Trim(), Config = config, IsEnabled = _working.IsEnabled,
            });
        }
        else
        {
            var existing = await db.IngestionEndpoints.FirstAsync(e => e.Id == _working.Id);
            existing.Type = _working.Type;
            existing.Name = _working.Name.Trim();
            existing.Config = config;
            existing.IsEnabled = _working.IsEnabled;
        }

        await db.SaveChangesAsync();
        _editOpen = false;
        Snackbar.Add("Saved.", Severity.Success);
        await LoadAsync();
    }

    private async Task DeleteAsync(IngestionEndpoint endpoint)
    {
        await using var db = await DbFactory.CreateDbContextAsync();
        var sourceCount = await db.MeterSources.CountAsync(s => s.EndpointId == endpoint.Id);
        // Routing is endpoint-scoped, so "unlinked" now means those sources stop ingesting entirely
        // rather than falling back to any broker. Say so plainly.
        var note = sourceCount > 0
            ? $" {sourceCount} source(s) use it and will stop ingesting until reassigned to another connector."
            : "";
        if (!await Confirm.DeleteAsync(DialogService, "Delete connector", $"Delete '{endpoint.Name}'?{note}"))
        {
            return;
        }

        await db.IngestionEndpoints.Where(e => e.Id == endpoint.Id).ExecuteDeleteAsync();
        Snackbar.Add("Deleted.", Severity.Success);
        await LoadAsync();
    }

    private static string? Trim(string? value) => string.IsNullOrWhiteSpace(value) ? null : value.Trim();

    /// <summary>
    /// Whether two URLs address the same host. Compares scheme, host and port rather than the raw
    /// string, so a trailing slash or a path tweak does not force the token to be re-typed. Fails
    /// closed: anything unparsable counts as a different origin.
    /// </summary>
    private static bool SameOrigin(string? a, string? b) =>
        Uri.TryCreate(a, UriKind.Absolute, out var left)
        && Uri.TryCreate(b, UriKind.Absolute, out var right)
        && string.Equals(left.Scheme, right.Scheme, StringComparison.OrdinalIgnoreCase)
        && string.Equals(left.Host, right.Host, StringComparison.OrdinalIgnoreCase)
        && left.Port == right.Port;

    /// <summary>
    /// Encrypts a newly typed secret, or keeps the stored ciphertext when the field was left blank.
    /// The plaintext is never sent to the browser, so blank means "unchanged", not "cleared".
    /// </summary>
    private string? ProtectOrKeep(string? typed, string? existingCiphertext) =>
        string.IsNullOrWhiteSpace(typed) ? existingCiphertext : Secrets.Protect(typed);

    private static IReadOnlyList<string> SplitTopics(string? csv) =>
        string.IsNullOrWhiteSpace(csv) ? [] : [.. csv.Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)];

    private sealed class EditModel
    {
        public int Id { get; set; }
        public EndpointType Type { get; set; } = EndpointType.HomeAssistant;
        public string Name { get; set; } = "";
        public bool IsEnabled { get; set; } = true;

        // Home Assistant
        public string? BaseUrl { get; set; }
        public string? TokenEnv { get; set; }
        public bool UseWebSocket { get; set; }
        public string? TestEntityId { get; set; }

        /// <summary>True to store the token here (encrypted); false to name an env var.</summary>
        public bool UseDirectToken { get; set; }

        /// <summary>Typed token. Always blank on load — a stored secret is never sent to the browser.</summary>
        public string? Token { get; set; }

        /// <summary>Stored ciphertext, round-tripped so leaving <see cref="Token"/> blank keeps it.</summary>
        public string? TokenEnc { get; set; }

        /// <summary>Base URL as saved, so an edited one can be told from the token's own host.</summary>
        public string? SavedBaseUrl { get; set; }

        public bool HasStoredToken => !string.IsNullOrWhiteSpace(TokenEnc);

        // MQTT broker
        public string? Host { get; set; } = "localhost";
        public int Port { get; set; } = 1883;
        public bool Tls { get; set; }
        public string? UsernameEnv { get; set; }
        public string? PasswordEnv { get; set; }
        public string? ExtraTopics { get; set; }

        public bool UseDirectCredentials { get; set; }

        /// <summary>Username entered directly — not a secret, so shown when editing.</summary>
        public string? Username { get; set; }

        public string? Password { get; set; }

        public string? PasswordEnc { get; set; }

        public bool HasStoredPassword => !string.IsNullOrWhiteSpace(PasswordEnc);
    }
}