using JobTrackerApi.Models;
using JobTrackerApi.Services;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;

namespace JobTrackerApi.Controllers;

// Phase 4 — Career Workspace Builder API. Every endpoint reads the master profile through
// ICareerProfileService and renders through the data-driven theme engine; none of them store career
// data. docs/architecture/cv-builder.md.
[ApiController]
[Route("api/cv")]
[Authorize(AuthenticationSchemes = "local")]
public sealed class CvVariantController : ControllerBase
{
    private readonly UserManager<ApplicationUser> _users;
    private readonly ICvVariantService _variants;
    private readonly ICvPdfExporter _pdf;
    private readonly ISummarizerService _ai;

    public CvVariantController(UserManager<ApplicationUser> users, ICvVariantService variants, ICvPdfExporter pdf, ISummarizerService ai)
    {
        _users = users;
        _variants = variants;
        _pdf = pdf;
        _ai = ai;
    }

    public sealed record VariantDto(int Id, string Name, CvVariantSettings Settings, bool IsPublic, string PublicSlug, int Version, int? JobApplicationId, DateTimeOffset UpdatedAtUtc);
    public sealed record CreateVariantRequest(string? Name, int? JobApplicationId, CvVariantSettings? Settings);
    public sealed record SaveVariantRequest(string? Name, CvVariantSettings? Settings, string? Source);
    public sealed record PublicToggleRequest(bool IsPublic);
    public sealed record DuplicateRequest(string? Name);
    public sealed record PreviewRequest(CvVariantSettings? Settings);
    public sealed record RenderDto(string ThemeId, string Html, string SuggestedFileName);
    public sealed record AiAssistRequest(string? Action, string? Text, string? Context, string? Role, string? Language);
    public sealed record AiAssistResult(string Original, string Result);

    [HttpGet("themes")]
    public async Task<ActionResult<IEnumerable<object>>> GetThemes()
    {
        var user = await _users.GetUserAsync(User);
        if (user is null) return Unauthorized();
        var premiumThemes = AccountPlans.ForRoles(await _users.GetRolesAsync(user)).PremiumThemes;
        var themes = CvThemeCatalog.Themes.Select(t => new
        {
            id = t.Id,
            name = t.Name,
            category = t.Category,
            description = t.Description,
            layout = t.Layout,
            accent = t.Accent,
            photoShape = t.PhotoShape,
            supportsIcons = t.DefaultIcons,
            atsFriendly = t.AtsFriendly,
            premium = t.Premium,
            available = premiumThemes || !t.Premium,
            swatches = new[] { t.Accent, t.SidebarBg, t.Paper },
        });
        return Ok(themes);
    }

    // The master profile as sections+entries (with ItemKeys) — the Content tab reads this to render
    // editable rows without duplicating the profile shape on the client.
    [HttpGet("outline")]
    public async Task<ActionResult<CvRenderModel>> Outline(CancellationToken ct)
    {
        var user = await _users.GetUserAsync(User);
        if (user is null) return Unauthorized();
        return Ok(await _variants.OutlineAsync(user.Id, Person(user), ct));
    }

    [HttpGet("variants")]
    public async Task<ActionResult<IEnumerable<CvVariantSummary>>> List(CancellationToken ct)
    {
        var user = await _users.GetUserAsync(User);
        if (user is null) return Unauthorized();
        return Ok(await _variants.ListAsync(user.Id, ct));
    }

    [HttpPost("variants")]
    public async Task<ActionResult<VariantDto>> Create([FromBody] CreateVariantRequest? request, CancellationToken ct)
    {
        var user = await _users.GetUserAsync(User);
        if (user is null) return Unauthorized();
        if (request?.Settings is not null && !CvThemeCatalog.Exists(request.Settings.ThemeId))
            return BadRequest("Unknown theme.");
        if (request?.Settings is not null && !await CanUseThemeAsync(user, request.Settings.ThemeId))
            return StatusCode(StatusCodes.Status403Forbidden, "This theme requires Premium.");
        var variant = await _variants.CreateAsync(user.Id, request?.Name, request?.JobApplicationId, request?.Settings, ct);
        return Ok(ToDto(variant));
    }

    [HttpGet("variants/{id:int}")]
    public async Task<ActionResult<VariantDto>> Get(int id, CancellationToken ct)
    {
        var user = await _users.GetUserAsync(User);
        if (user is null) return Unauthorized();
        var variant = await _variants.GetAsync(user.Id, id, ct);
        return variant is null ? NotFound() : Ok(ToDto(variant));
    }

    [HttpPut("variants/{id:int}")]
    public async Task<ActionResult<VariantDto>> Save(int id, [FromBody] SaveVariantRequest request, CancellationToken ct)
    {
        var user = await _users.GetUserAsync(User);
        if (user is null) return Unauthorized();
        var settings = CvVariantSettingsJson.Normalize(request.Settings);
        if (!CvThemeCatalog.Exists(settings.ThemeId)) return BadRequest("Unknown theme.");
        if (!await CanUseThemeAsync(user, settings.ThemeId))
        {
            var current = await _variants.GetAsync(user.Id, id, ct);
            if (current is null) return NotFound();
            if (!string.Equals(CvVariantSettingsJson.Deserialize(current.SettingsJson).ThemeId, settings.ThemeId, StringComparison.OrdinalIgnoreCase))
                return StatusCode(StatusCodes.Status403Forbidden, "This theme requires Premium.");
        }
        var variant = await _variants.SaveAsync(user.Id, id, request.Name, settings, request.Source ?? "autosave", ct);
        return variant is null ? NotFound() : Ok(ToDto(variant));
    }

    [HttpDelete("variants/{id:int}")]
    public async Task<IActionResult> Delete(int id, CancellationToken ct)
    {
        var user = await _users.GetUserAsync(User);
        if (user is null) return Unauthorized();
        return await _variants.DeleteAsync(user.Id, id, ct) ? NoContent() : NotFound();
    }

    [HttpPost("variants/{id:int}/duplicate")]
    public async Task<ActionResult<VariantDto>> Duplicate(int id, [FromBody] DuplicateRequest? request, CancellationToken ct)
    {
        var user = await _users.GetUserAsync(User);
        if (user is null) return Unauthorized();
        var variant = await _variants.DuplicateAsync(user.Id, id, request?.Name, ct);
        return variant is null ? NotFound() : Ok(ToDto(variant));
    }

    [HttpPut("variants/{id:int}/public")]
    public async Task<ActionResult<VariantDto>> SetPublic(int id, [FromBody] PublicToggleRequest request, CancellationToken ct)
    {
        var user = await _users.GetUserAsync(User);
        if (user is null) return Unauthorized();
        var variant = await _variants.SetPublicAsync(user.Id, id, request.IsPublic, ct);
        return variant is null ? NotFound() : Ok(ToDto(variant));
    }

    [HttpGet("variants/{id:int}/versions")]
    public async Task<ActionResult<IEnumerable<CvVariantVersionInfo>>> Versions(int id, CancellationToken ct)
    {
        var user = await _users.GetUserAsync(User);
        if (user is null) return Unauthorized();
        return Ok(await _variants.ListVersionsAsync(user.Id, id, ct));
    }

    [HttpPost("variants/{id:int}/versions/{version:int}/restore")]
    public async Task<ActionResult<VariantDto>> Restore(int id, int version, CancellationToken ct)
    {
        var user = await _users.GetUserAsync(User);
        if (user is null) return Unauthorized();
        var variant = await _variants.RestoreVersionAsync(user.Id, id, version, ct);
        return variant is null ? NotFound() : Ok(ToDto(variant));
    }

    [HttpGet("variants/{id:int}/preview")]
    public async Task<ActionResult<RenderDto>> Preview(int id, CancellationToken ct)
    {
        var user = await _users.GetUserAsync(User);
        if (user is null) return Unauthorized();
        var render = await _variants.RenderAsync(user.Id, id, Person(user), ct);
        return render is null ? NotFound() : Ok(new RenderDto(render.ThemeId, render.Html, render.SuggestedFileName));
    }

    // Live preview for unsaved builder settings.
    [HttpPost("preview")]
    public async Task<ActionResult<RenderDto>> PreviewSettings([FromBody] PreviewRequest request, CancellationToken ct)
    {
        var user = await _users.GetUserAsync(User);
        if (user is null) return Unauthorized();
        var settings = CvVariantSettingsJson.Normalize(request.Settings);
        if (!CvThemeCatalog.Exists(settings.ThemeId)) return BadRequest("Unknown theme.");
        var render = await _variants.RenderSettingsAsync(user.Id, settings, Person(user), ct);
        return Ok(new RenderDto(render.ThemeId, render.Html, render.SuggestedFileName));
    }

    [HttpPost("variants/{id:int}/export-pdf")]
    public async Task<IActionResult> ExportPdf(int id, CancellationToken ct)
    {
        var user = await _users.GetUserAsync(User);
        if (user is null) return Unauthorized();
        var render = await _variants.RenderAsync(user.Id, id, Person(user), ct);
        if (render is null) return NotFound();
        var artifact = await _pdf.ExportAsync(new TailoredCvRenderResult(render.ThemeId, render.SuggestedFileName, render.Html), ct);
        return File(artifact.Bytes, "application/pdf", artifact.FileName);
    }

    // AI assistance on any text area. Never mutates the profile or variant — returns a suggestion the
    // user reviews and applies themselves. Reuses the existing provider abstraction (ISummarizerService).
    [HttpPost("ai/assist")]
    public async Task<ActionResult<AiAssistResult>> AiAssist([FromBody] AiAssistRequest request, CancellationToken ct)
    {
        var user = await _users.GetUserAsync(User);
        if (user is null) return Unauthorized();
        var text = (request.Text ?? string.Empty).Trim();
        if (text.Length == 0) return BadRequest("Provide text to work on.");

        var instruction = BuildAiInstruction(request.Action, request.Role, request.Language, request.Context);
        var result = await _ai.SummarizeSectionAsync(instruction, text, 1200, 300);
        if (string.IsNullOrWhiteSpace(result))
        {
            var metrics = await _ai.GetMetricsAsync(ct);
            return StatusCode(StatusCodes.Status502BadGateway, metrics.Healthy
                ? "The AI service returned no usable text."
                : "The AI service is unavailable right now.");
        }
        return Ok(new AiAssistResult(text, result.Trim()));
    }

    private static string BuildAiInstruction(string? action, string? role, string? language, string? context)
    {
        var target = string.IsNullOrWhiteSpace(role) ? null : role.Trim();
        var lang = string.IsNullOrWhiteSpace(language) ? "the same language as the input" : language.Trim();
        var extra = string.IsNullOrWhiteSpace(context) ? string.Empty : $" Context: {context.Trim()}.";
        var task = (action ?? "improve").Trim().ToLowerInvariant() switch
        {
            "professional" => "Rewrite the text in a more professional, confident tone.",
            "shorten" => "Make the text more concise without losing meaning.",
            "expand" => "Expand the text with more concrete, relevant detail — but never invent facts.",
            "grammar" => "Fix grammar, spelling and punctuation only. Keep wording and meaning.",
            "ats" => "Rewrite for ATS keyword optimisation: strong action verbs, quantified impact, clear phrasing. Do not invent facts.",
            "bullets" => "Rewrite as 3–5 tight achievement bullet points, each starting with a strong action verb. Do not invent facts.",
            "summary" => "Write a concise professional summary (2–3 sentences) from this text. Do not invent facts.",
            "rewrite" => "Rewrite the text more clearly and compellingly, preserving all facts.",
            "tailor" => $"Rewrite the text to align with the target role{(target is null ? string.Empty : $" '{target}'")}, emphasising the most relevant experience. Do not invent facts.",
            _ => "Improve the clarity, impact and phrasing of the text while preserving all facts.",
        };
        return $"{task} Preserve every factual claim — never invent employers, titles, dates, or metrics. Write in {lang}. Return only the rewritten text with no preamble.{extra}";
    }

    private async Task<bool> CanUseThemeAsync(ApplicationUser user, string? themeId) =>
        CvThemeCatalog.CanUse(themeId, AccountPlans.ForRoles(await _users.GetRolesAsync(user)).PremiumThemes);

    private static CvRenderPerson Person(ApplicationUser user)
    {
        var name = string.Join(" ", new[] { user.FirstName?.Trim(), user.LastName?.Trim() }.Where(x => !string.IsNullOrWhiteSpace(x)));
        if (string.IsNullOrWhiteSpace(name)) name = user.DisplayName?.Trim();
        if (string.IsNullOrWhiteSpace(name)) name = user.UserName?.Trim();
        if (string.IsNullOrWhiteSpace(name)) name = user.Email?.Trim();
        if (string.IsNullOrWhiteSpace(name)) name = "Your Name";
        return new CvRenderPerson(name!, AvatarStorage.Resolve(user.AvatarImageDataUrl));
    }

    private static VariantDto ToDto(CvVariant v) => new(
        v.Id, v.Name, CvVariantSettingsJson.Deserialize(v.SettingsJson), v.IsPublic, v.PublicSlug, v.Version, v.JobApplicationId, v.UpdatedAtUtc);
}