// videoutil.go implements the videogen.VideoBackgroundRemovalProvider and
// videogen.VideoUpscaleProvider surfaces against the mediautils shim reached
// through llama-swap's /upstream passthrough (ADR-0025):
//
//	matte    POST /upstream/<id>/v1/video/matte    (Robust Video Matting)
//	upscale  POST /upstream/<id>/v1/video/upscale  (per-frame Real-ESRGAN)
//
// Both are one-file multipart in, encoded clip out — the video siblings of
// mediautil.go's still-image surfaces.
package llamaswap

import (
	"context"
	"fmt"
	"mime"
	"net/http"
	"strconv"
	"strings"

	"gitea.stevedudenhoeffer.com/steve/majordomo/llm"
	"gitea.stevedudenhoeffer.com/steve/majordomo/videogen"
)

// --- video background removal (matting) ---

// VideoBackgroundRemoverModel implements
// videogen.VideoBackgroundRemovalProvider against the mediautils shim's
// POST /v1/video/matte. The id selects which upstream llama-swap loads.
func (p *Provider) VideoBackgroundRemoverModel(id string, opts ...videogen.VideoBackgroundRemoverModelOption) (videogen.VideoBackgroundRemover, error) {
	if err := p.requireBaseURL(); err != nil {
		return nil, err
	}
	_ = videogen.ApplyVideoBackgroundRemoverModelOptions(opts)
	return &videoMatteModel{p: p, id: id}, nil
}

type videoMatteModel struct {
	p  *Provider
	id string
}

// RemoveVideoBackground implements videogen.VideoBackgroundRemover.
func (m *videoMatteModel) RemoveVideoBackground(ctx context.Context, req videogen.VideoBackgroundRemovalRequest, opts ...videogen.VideoBackgroundRemovalOption) (*videogen.Result, error) {
	req = req.Apply(opts...)
	if len(req.Video) == 0 {
		return nil, fmt.Errorf("%w: video background removal requires a video", llm.ErrUnsupported)
	}
	if req.Output != "" && req.Output != "greenscreen_mp4" && req.Output != "alpha_webm" {
		return nil, fmt.Errorf("%w: video matte output must be \"greenscreen_mp4\" or \"alpha_webm\", got %q", llm.ErrUnsupported, req.Output)
	}
	path, err := upstreamPath(m.id, "/v1/video/matte")
	if err != nil {
		return nil, err
	}
	body, contentType, err := buildMultipart("build video-matte form",
		filePart{field: "file", filename: videoInputFilename(req.Filename, req.MIME), data: req.Video},
		[]formField{{"output", req.Output, false}})
	if err != nil {
		return nil, err
	}
	raw, respType, err := m.p.doRaw(ctx, http.MethodPost, path, m.id, contentType, body, maxVideoResponseBytes)
	if err != nil {
		return nil, err
	}
	return singleVideoResult(m.p.name, m.id, "video matte", raw, respType)
}

// --- video upscale ---

// VideoUpscalerModel implements videogen.VideoUpscaleProvider against the
// mediautils shim's POST /v1/video/upscale.
func (p *Provider) VideoUpscalerModel(id string, opts ...videogen.VideoUpscalerModelOption) (videogen.VideoUpscaler, error) {
	if err := p.requireBaseURL(); err != nil {
		return nil, err
	}
	_ = videogen.ApplyVideoUpscalerModelOptions(opts)
	return &videoUpscaleModel{p: p, id: id}, nil
}

type videoUpscaleModel struct {
	p  *Provider
	id string
}

// UpscaleVideo implements videogen.VideoUpscaler.
func (m *videoUpscaleModel) UpscaleVideo(ctx context.Context, req videogen.VideoUpscaleRequest, opts ...videogen.VideoUpscaleOption) (*videogen.Result, error) {
	req = req.Apply(opts...)
	if len(req.Video) == 0 {
		return nil, fmt.Errorf("%w: video upscale requires a video", llm.ErrUnsupported)
	}
	if req.Scale != 0 && req.Scale != 2 && req.Scale != 4 {
		return nil, fmt.Errorf("%w: video upscale scale must be 2 or 4, got %d", llm.ErrUnsupported, req.Scale)
	}
	path, err := upstreamPath(m.id, "/v1/video/upscale")
	if err != nil {
		return nil, err
	}
	scale := ""
	if req.Scale != 0 {
		scale = strconv.Itoa(req.Scale)
	}
	body, contentType, err := buildMultipart("build video-upscale form",
		filePart{field: "file", filename: videoInputFilename(req.Filename, req.MIME), data: req.Video},
		[]formField{{"scale", scale, false}})
	if err != nil {
		return nil, err
	}
	raw, respType, err := m.p.doRaw(ctx, http.MethodPost, path, m.id, contentType, body, maxVideoResponseBytes)
	if err != nil {
		return nil, err
	}
	return singleVideoResult(m.p.name, m.id, "video upscale", raw, respType)
}

// videoInputFilename picks the multipart filename hint for a caller-supplied
// video: the caller's (sanitized — upload metadata is untrusted), else one
// derived from the MIME subtype ("video.mp4"), else "video". Mirrors
// transcriptionFilename.
func videoInputFilename(filename, mimeType string) string {
	if name := sanitizeFilename(filename); name != "" {
		return name
	}
	mt := strings.ToLower(strings.TrimSpace(mimeType))
	if parsed, _, err := mime.ParseMediaType(mt); err == nil {
		mt = parsed
	}
	switch mt {
	case "video/mp4":
		return "video.mp4"
	case "video/webm":
		return "video.webm"
	case "video/quicktime":
		return "video.mov"
	case "video/x-matroska":
		return "video.mkv"
	default:
		return "video"
	}
}