using System.Security.Cryptography;
using System.Text;
using System.Text.Json;
using ClawdDotNet.Core.Config;
using ClawdDotNet.Core.Organisation;

namespace ClawdDotNet.App.Services;

/// <summary>#691: What the human may change when importing a template — models and budgets fit one house, not every house.</summary>
public sealed record TemplateOverrides(
    string? Model = null,
    IReadOnlyDictionary<string, string>? Models = null,
    decimal? BudgetFactor = null);

public sealed record TemplatePreviewUnit(string Id, string Name, string? ParentId, string? LeaderAgentId, string Path);

public sealed record TemplatePreviewAgent(
    string AgentId, string DisplayName, string? UnitId, string Model, decimal DailyCostUsd, long DailyTokens,
    IReadOnlyList<string> Tools, string Identity, string Soul);

/// <summary>#691: What an import would do — and what stands in its way. Nothing is written for it.</summary>
public sealed record TemplatePreview(
    string Name,
    string Version,
    string Fingerprint,
    IReadOnlyList<string> Problems,
    IReadOnlyList<string> Warnings,
    IReadOnlyList<TemplatePreviewUnit> Units,
    IReadOnlyList<TemplatePreviewAgent> Agents,
    IReadOnlyList<CredentialNeed> Credentials)
{
    public bool CanImport => Problems.Count == 0;
}

public sealed partial class OrgAdministration
{
    // ─── templates (#691) ───

    /// <summary>The organisation of this instance as a template file — never with credentials.</summary>
    public OrgTemplate ExportTemplate(string name, string description = "")
        => OrgTemplates.Export(host.Instance, string.IsNullOrWhiteSpace(name) ? "Organisation" : name, description,
            unitId => host.Doctrines?.Current(unitId)?.Text, DateTime.UtcNow);

    /// <summary>
    /// What importing <paramref name="template"/> would create, with the models and budgets after
    /// the overrides — and the problems that stop it: a broken template, ids or names the
    /// instance already has, tools beyond a unit's ceiling.
    /// </summary>
    public TemplatePreview PreviewTemplate(OrgTemplate template, TemplateOverrides? overrides = null)
    {
        overrides ??= new TemplateOverrides();
        var problems = OrgTemplates.Problems(template).ToList();
        var sound = problems.Count == 0;
        var warnings = new List<string>();

        foreach (var unit in template.Units)
        {
            if (FindUnit(unit.Id) is not null)
                problems.Add($"This instance already has a unit '{unit.Id}'.");
            else if (Chart.Workspace(unit.Id) is not null)
                problems.Add($"This instance already has a workspace '{unit.Id}' — the unit's own workspace would carry that id.");
            else if (!WorkspaceLayout.IsValidId(unit.Id))
                problems.Add($"'{unit.Id}' is reserved and cannot be a unit id.");
        }
        foreach (var agent in template.Agents)
        {
            if (host.AgentAdmin.Find(agent.AgentId) is not null)
                problems.Add($"This instance already has an agent '{agent.AgentId}'.");
            else if (host.Instance.Agents.Any(a => Same(a.DisplayName.Trim(), agent.DisplayName.Trim())))
                problems.Add($"This instance already has an agent named '{agent.DisplayName}' — the name gives the folder.");
        }
        if (overrides.BudgetFactor is <= 0)
            problems.Add("The budget factor must be above 0.");

        // The ceilings of the template's own units apply to the template's own agents — walked
        // only in a sound tree: a circle would never end.
        var chart = new OrgChart(sound ? template.Units : [], template.Agents.Select(a => new AgentConfig { AgentId = a.AgentId, UnitId = a.UnitId }));
        foreach (var agent in template.Agents)
        {
            if (sound && chart.ToolCeiling(agent.UnitId) is { } ceiling)
                foreach (var tool in agent.Tools.Keys.Where(t => !ceiling.Contains(t)))
                    problems.Add($"Agent '{agent.AgentId}' has {tool}, beyond the tool ceiling of its unit.");
            foreach (var tool in agent.Tools.Keys.Where(t => host.Tools.Get(t) is null))
                warnings.Add($"{tool} (agent '{agent.AgentId}') is not loaded in this instance — the setting is kept, the tool does nothing.");
        }
        if (template.Credentials.Count > 0)
            warnings.Add($"{template.Credentials.Count} credential(s) must be filled in after the import — the template brings none.");
        warnings.Add("The Identity and Soul texts of this template become prompts. Read them: whoever wrote the template writes your agents' instructions.");

        var units = template.Units
            .Select(u => new TemplatePreviewUnit(u.Id, u.Name, u.ParentId, u.LeaderAgentId, sound ? chart.PathOf(u.Id) : u.Name))
            .OrderBy(u => u.Path, StringComparer.OrdinalIgnoreCase)
            .ToList();
        var agents = template.Agents.Select(a =>
        {
            var budget = Scaled(a.Budget, overrides.BudgetFactor);
            return new TemplatePreviewAgent(a.AgentId, a.DisplayName, a.UnitId, ModelFor(a, overrides),
                budget.DailyCostUsd, budget.DailyTokens, a.Tools.Keys.Order(StringComparer.OrdinalIgnoreCase).ToList(), a.Identity, a.Soul);
        }).ToList();

        return new TemplatePreview(template.Name, template.Version, Fingerprint(template), problems, warnings, units, agents, template.Credentials);
    }

    /// <summary>
    /// Imports the template: units with their rules and workspaces, agents with their texts,
    /// tools, models and budgets, the doctrines. Only with <paramref name="confirmed"/> — the
    /// texts are someone else's instructions — and only if the preview has no problem. Every
    /// unit and agent keeps the template as its origin; credentials stay empty.
    /// </summary>
    public async Task<AdminResult> ImportTemplateAsync(OrgTemplate template, TemplateOverrides? overrides, bool confirmed, string source, string reason, CancellationToken ct)
    {
        overrides ??= new TemplateOverrides();
        var preview = PreviewTemplate(template, overrides);
        if (!preview.CanImport)
            return AdminResult.Failure("The template cannot be imported: " + string.Join(" ", preview.Problems.Take(5)));
        if (!confirmed)
            return AdminResult.Failure("Confirm the import: the template's Identity and Soul texts become your agents' prompts.");

        var origin = $"{template.Name} v{template.Version} ({preview.Fingerprint})" + (string.IsNullOrWhiteSpace(source) ? "" : $" from {source.Trim()}");

        // Parents before children, so every unit finds the one it hangs under.
        var chart = new OrgChart(template.Units, []);
        foreach (var unit in template.Units.OrderBy(u => chart.Depth(u.Id)))
        {
            var copy = JsonSerializer.Deserialize<UnitConfig>(JsonSerializer.Serialize(unit))!;
            copy.TemplateOrigin = origin;
            host.Instance.Units.Add(copy);
            host.Instance.Workspaces.Add(OwnWorkspace(copy.Id, copy.Name));
        }

        var created = new List<string>();
        foreach (var agent in template.Agents)
        {
            var model = ModelFor(agent, overrides);
            var added = host.AgentAdmin.Add(new NewAgent(agent.AgentId, agent.DisplayName, model, agent.Description, agent.UnitId));
            if (!added.Ok || host.AgentAdmin.Find(agent.AgentId) is not { } config)
                return AdminResult.Failure($"Stopped at agent '{agent.AgentId}': {added.Message} Created so far: {string.Join(", ", created)}.");

            // The template's values, not the unit's defaults — the template says what it means.
            config.Model = model;
            config.Budget = Scaled(agent.Budget, overrides.BudgetFactor);
            config.Identity = agent.Identity;
            config.Soul = agent.Soul;
            config.TemplateOrigin = origin;
            config.Tools = agent.Tools.ToDictionary(
                t => t.Key,
                t => JsonSerializer.Deserialize<Dictionary<string, object?>>(t.Value.ToJsonString()) ?? new Dictionary<string, object?>(),
                StringComparer.OrdinalIgnoreCase);
            host.AgentAdmin.PersistAgent(config);
            created.Add(agent.AgentId);
        }

        if (host.Doctrines is { } doctrines)
            foreach (var (unitId, text) in template.Doctrines)
                if (!string.IsNullOrWhiteSpace(text))
                    await doctrines.SetAsync(unitId, text.Length > SqliteDoctrineStore.MaxLength ? text[..SqliteDoctrineStore.MaxLength] : text,
                        "template", null, $"Imported with {origin}", ct);

        Save(null, "template_import", new
        {
            origin, units = template.Units.Select(u => u.Id), agents = created,
            overrides.Model, overrides.BudgetFactor, credentials = template.Credentials.Count
        }, reason);

        return AdminResult.Success(
            $"Imported '{template.Name}': {template.Units.Count} unit(s), {created.Count} agent(s)."
            + (template.Credentials.Count == 0 ? "" : $" Fill in {template.Credentials.Count} credential(s) in the agents' tool settings before they run."));
    }

    private static string ModelFor(TemplateAgent agent, TemplateOverrides overrides)
        => overrides.Models?.GetValueOrDefault(agent.AgentId) is { Length: > 0 } own ? own.Trim()
            : !string.IsNullOrWhiteSpace(overrides.Model) ? overrides.Model.Trim()
            : string.IsNullOrWhiteSpace(agent.Model) ? new AgentConfig().Model
            : agent.Model;

    private static AgentBudget Scaled(AgentBudget budget, decimal? factor) => new()
    {
        DailyCostUsd = factor is { } f ? Math.Round(budget.DailyCostUsd * f, 2) : budget.DailyCostUsd,
        DailyTokens = factor is { } g ? (long)Math.Round(budget.DailyTokens * g) : budget.DailyTokens,
        WhenExhausted = budget.WhenExhausted
    };

    /// <summary>A short fingerprint of the template's content — which version of it came in.</summary>
    private static string Fingerprint(OrgTemplate template)
        => Convert.ToHexString(SHA256.HashData(Encoding.UTF8.GetBytes(JsonSerializer.Serialize(template, OrgTemplates.Json))))[..12].ToLowerInvariant();
}