using Gateway.Data;
using Gateway.Security;
using Microsoft.AspNetCore.Mvc;
using System.Text.Json;

namespace Gateway.Controllers;

/// <summary>
/// Campaign intelligence endpoints: health overview, budget pacing, 
/// and post-campaign analysis.
///
/// SECURITY MODEL:
///   - Every endpoint requires authenticated session (via middleware)
///   - Initiative endpoints verify ownership before data access
///   - Client-level endpoints scoped via injected ClientContext
///   - ClientId is always injected server-side, never from request body
/// </summary>
[ApiController]
[Route("api/intelligence")]
public sealed class CampaignIntelligenceController : ControllerBase
{
    private readonly SqlService _sql;
    private readonly ClientContext _client;
    private readonly AuthorizationGuard _guard;
    private readonly ILogger<CampaignIntelligenceController> _log;

    public CampaignIntelligenceController(
        SqlService sql,
        ClientContext client,
        AuthorizationGuard guard,
        ILogger<CampaignIntelligenceController> log)
    {
        _sql = sql;
        _client = client;
        _guard = guard;
        _log = log;
    }

    // ────────────────────────────────────────────────
    // Campaign Health Overview
    // ────────────────────────────────────────────────

    /// <summary>
    /// Get health overview for all active initiatives.
    /// Returns green/yellow/red status per channel campaign based on active recommendations.
    /// </summary>
    [HttpGet("health")]
    public async Task<IActionResult> Health(CancellationToken ct)
    {
        var (ok, err) = _guard.RequireAuth();
        if (!ok) return Unauthorized(new { ok = false, error = err });

        return await Exec(SqlNames.Procs.CampaignIntelligence, "health",
            JsonSerializer.Serialize(new { clientId = _client.ClientId }), ct);
    }

    // ────────────────────────────────────────────────
    // Budget Pacing
    // ────────────────────────────────────────────────

    /// <summary>
    /// Get budget pacing analysis for an initiative.
    /// Shows actual vs expected spend velocity with projections.
    /// </summary>
    [HttpGet("{initiativeId:long}/pacing")]
    public async Task<IActionResult> Pacing(long initiativeId, CancellationToken ct)
    {
        var ownership = await _guard.VerifyInitiativeOwnerAsync(initiativeId, ct);
        if (!ownership.IsAllowed)
            return NotFound(new { ok = false, error = ownership.Error });

        return await Exec(SqlNames.Procs.CampaignIntelligence, "pacing",
            JsonSerializer.Serialize(new { initiativeId }), ct);
    }

    // ────────────────────────────────────────────────
    // Post-Campaign Report
    // ────────────────────────────────────────────────

    /// <summary>
    /// Comprehensive post-campaign analysis.
    /// Cross-platform comparison with daily trends, efficiency metrics,
    /// and recommendation history.
    /// </summary>
    [HttpGet("{initiativeId:long}/report")]
    public async Task<IActionResult> PostCampaignReport(long initiativeId, CancellationToken ct)
    {
        var ownership = await _guard.VerifyInitiativeOwnerAsync(initiativeId, ct);
        if (!ownership.IsAllowed)
            return NotFound(new { ok = false, error = ownership.Error });

        return await Exec(SqlNames.Procs.CampaignIntelligence, "postCampaign",
            JsonSerializer.Serialize(new { initiativeId }), ct);
    }

    // ────────────────────────────────────────────────
    // Metric Snapshots (internal / polling service)
    // ────────────────────────────────────────────────

    /// <summary>
    /// Record an intraday metric snapshot for pacing analysis.
    /// Called by the background polling service between daily aggregations.
    /// Admin-only endpoint.
    /// </summary>
    [HttpPost("snapshot")]
    public async Task<IActionResult> Snapshot([FromBody] SnapshotRequest request, CancellationToken ct)
    {
        var (ok, err) = _guard.RequireServiceKey();
        if (!ok) return StatusCode(403, new { ok = false, error = err });

        return await Exec(SqlNames.Procs.CampaignIntelligence, "snapshot",
            JsonSerializer.Serialize(new
            {
                channelCampaignId = request.ChannelCampaignId,
                date = request.Date,
                impressions = request.Impressions,
                clicks = request.Clicks,
                spend = request.Spend,
                conversions = request.Conversions
            }), ct);
    }

    /// <summary>
    /// Batch insert intraday snapshots.
    /// Admin-only endpoint.
    /// </summary>
    [HttpPost("snapshot/batch")]
    public async Task<IActionResult> SnapshotBatch([FromBody] SnapshotBatchRequest request, CancellationToken ct)
    {
        var (ok, err) = _guard.RequireServiceKey();
        if (!ok) return StatusCode(403, new { ok = false, error = err });

        return await Exec(SqlNames.Procs.CampaignIntelligence, "snapshotBatch",
            JsonSerializer.Serialize(new { snapshots = request.Snapshots }), ct);
    }

    // ────────────────────────────────────────────────
    // Helpers
    // ────────────────────────────────────────────────

    private async Task<IActionResult> Exec(string proc, string action, string rqst, CancellationToken ct)
    {
        try
        {
            var resp = await _sql.ExecProcAsync(proc, action, rqst, ct: ct);
            if (string.IsNullOrWhiteSpace(resp))
                return StatusCode(500, new { ok = false, error = "Service unavailable" });

            using var doc = JsonDocument.Parse(resp);
            var root = doc.RootElement;

            if (root.TryGetProperty("ok", out var okProp) && !okProp.GetBoolean())
            {
                var error = root.TryGetProperty("error", out var errProp) ? errProp.GetString() : "Unknown error";
                if (error?.Contains("not found", StringComparison.OrdinalIgnoreCase) == true)
                    return NotFound(JsonSerializer.Deserialize<object>(resp));
                return BadRequest(JsonSerializer.Deserialize<object>(resp));
            }

            return Content(resp, "application/json");
        }
        catch (Exception ex)
        {
            _log.LogError(ex, "CampaignIntelligence {Action} error", action);
            return StatusCode(500, new { ok = false, error = "Service error" });
        }
    }
}

// ── DTOs ──

public sealed class SnapshotRequest
{
    public long? ChannelCampaignId { get; set; }
    public string? Date { get; set; }
    public long? Impressions { get; set; }
    public long? Clicks { get; set; }
    public decimal? Spend { get; set; }
    public decimal? Conversions { get; set; }
}

public sealed class SnapshotBatchRequest
{
    public object[]? Snapshots { get; set; }
}