using Unosquare.Swan;
using System;
using System.Text;

namespace Unosquare.RaspberryIO.Camera {
  /// <summary>
  /// Represents the raspivid camera settings for video capture functionality
  /// </summary>
  /// <seealso cref="CameraSettingsBase" />
  public class CameraVideoSettings : CameraSettingsBase {
    /// <inheritdoc />
    public override String CommandName => "raspivid";

    /// <summary>
    /// Use bits per second, so 10Mbits/s would be -b 10000000. For H264, 1080p30 a high quality bitrate would be 15Mbits/s or more. 
    /// Maximum bitrate is 25Mbits/s (-b 25000000), but much over 17Mbits/s won't show noticeable improvement at 1080p30.
    /// Default -1
    /// </summary>
    public Int32 CaptureBitrate { get; set; } = -1;

    /// <summary>
    /// Gets or sets the framerate.
    /// Default 25, range 2 to 30
    /// </summary>
    public Int32 CaptureFramerate { get; set; } = 25;

    /// <summary>
    /// Sets the intra refresh period (GoP) rate for the recorded video. H264 video uses a complete frame (I-frame) every intra 
    /// refresh period, from which subsequent frames are based. This option specifies the number of frames between each I-frame. 
    /// Larger numbers here will reduce the size of the resulting video, and smaller numbers make the stream less error-prone.
    /// </summary>
    public Int32 CaptureKeyframeRate { get; set; } = 25;

    /// <summary>
    /// Sets the initial quantisation parameter for the stream. Varies from approximately 10 to 40, and will greatly affect 
    /// the quality of the recording. Higher values reduce quality and decrease file size. Combine this setting with a 
    /// bitrate of 0 to set a completely variable bitrate.
    /// </summary>
    public Int32 CaptureQuantisation { get; set; } = 23;

    /// <summary>
    /// Gets or sets the profile.
    /// Sets the H264 profile to be used for the encoding.
    /// Default is Main mode
    /// </summary>
    public CameraH264Profile CaptureProfile { get; set; } = CameraH264Profile.Main;

    /// <summary>
    /// Forces the stream to include PPS and SPS headers on every I-frame. Needed for certain streaming cases 
    /// e.g. Apple HLS. These headers are small, so don't greatly increase the file size.
    /// </summary>
    /// <value>
    ///   <c>true</c> if [interleave headers]; otherwise, <c>false</c>.
    /// </value>
    public Boolean CaptureInterleaveHeaders { get; set; } = true;

    /// <summary>
    /// Switch on an option to display the preview after compression. This will show any compression artefacts in the preview window. In normal operation, 
    /// the preview will show the camera output prior to being compressed. This option is not guaranteed to work in future releases.
    /// </summary>
    /// <value>
    /// <c>true</c> if [capture display preview encoded]; otherwise, <c>false</c>.
    /// </value>
    public Boolean CaptureDisplayPreviewEncoded { get; set; } = false;

    /// <inheritdoc />
    public override String CreateProcessArguments() {
      StringBuilder sb = new StringBuilder(base.CreateProcessArguments());

      _ = sb.Append($" -pf {this.CaptureProfile.ToString().ToLowerInvariant()}");
      if(this.CaptureBitrate < 0) {
        _ = sb.Append($" -b {this.CaptureBitrate.Clamp(0, 25000000).ToString(Ci)}");
      }

      if(this.CaptureFramerate >= 2) {
        _ = sb.Append($" -fps {this.CaptureFramerate.Clamp(2, 30).ToString(Ci)}");
      }

      if(this.CaptureDisplayPreview && this.CaptureDisplayPreviewEncoded) {
        _ = sb.Append(" -e");
      }

      if(this.CaptureKeyframeRate > 0) {
        _ = sb.Append($" -g {this.CaptureKeyframeRate.ToString(Ci)}");
      }

      if(this.CaptureQuantisation >= 0) {
        _ = sb.Append($" -qp {this.CaptureQuantisation.Clamp(0, 40).ToString(Ci)}");
      }

      if(this.CaptureInterleaveHeaders) {
        _ = sb.Append(" -ih");
      }

      return sb.ToString();
    }
  }
}