package options

import (
	"log/slog"
	"maps"
	"net/http"
	"slices"
	"strconv"
	"strings"
	"time"

	"github.com/imgproxy/imgproxy/v3/ierrors"
	"github.com/imgproxy/imgproxy/v3/imagetype"
	"github.com/imgproxy/imgproxy/v3/imath"
	"github.com/imgproxy/imgproxy/v3/security"
	"github.com/imgproxy/imgproxy/v3/structdiff"
	"github.com/imgproxy/imgproxy/v3/vips"
)

const maxClientHintDPR = 8

type ExtendOptions struct {
	Enabled bool
	Gravity GravityOptions
}

type CropOptions struct {
	Width   float64
	Height  float64
	Gravity GravityOptions
}

type PaddingOptions struct {
	Enabled bool
	Top     int
	Right   int
	Bottom  int
	Left    int
}

type TrimOptions struct {
	Enabled   bool
	Threshold float64
	Smart     bool
	Color     vips.Color
	EqualHor  bool
	EqualVer  bool
}

type WatermarkOptions struct {
	Enabled  bool
	Opacity  float64
	Position GravityOptions
	Scale    float64
}

func (wo WatermarkOptions) ShouldReplicate() bool {
	return wo.Position.Type == GravityReplicate
}

type ProcessingOptions struct {
	defaultOptions *ProcessingOptions
	config         *Config

	ResizingType      ResizeType
	Width             int
	Height            int
	MinWidth          int
	MinHeight         int
	ZoomWidth         float64
	ZoomHeight        float64
	Dpr               float64
	Gravity           GravityOptions
	Enlarge           bool
	Extend            ExtendOptions
	ExtendAspectRatio ExtendOptions
	Crop              CropOptions
	Padding           PaddingOptions
	Trim              TrimOptions
	Rotate            int
	Format            imagetype.Type
	Quality           int
	FormatQuality     map[imagetype.Type]int
	MaxBytes          int
	Flatten           bool
	Background        vips.Color
	Blur              float32
	Sharpen           float32
	Pixelate          int
	StripMetadata     bool
	KeepCopyright     bool
	StripColorProfile bool
	AutoRotate        bool
	EnforceThumbnail  bool

	SkipProcessingFormats []imagetype.Type

	CacheBuster string

	Expires *time.Time

	Watermark WatermarkOptions

	PreferWebP  bool
	EnforceWebP bool
	PreferAvif  bool
	EnforceAvif bool
	PreferJxl   bool
	EnforceJxl  bool

	Filename         string
	ReturnAttachment bool

	Raw bool

	UsedPresets []string

	SecurityOptions security.Options
}

func newDefaultProcessingOptions(config *Config, security *security.Checker) *ProcessingOptions {
	po := ProcessingOptions{
		config: config,

		ResizingType:      ResizeFit,
		Width:             0,
		Height:            0,
		ZoomWidth:         1,
		ZoomHeight:        1,
		Gravity:           GravityOptions{Type: GravityCenter},
		Enlarge:           false,
		Extend:            ExtendOptions{Enabled: false, Gravity: GravityOptions{Type: GravityCenter}},
		ExtendAspectRatio: ExtendOptions{Enabled: false, Gravity: GravityOptions{Type: GravityCenter}},
		Padding:           PaddingOptions{Enabled: false},
		Trim:              TrimOptions{Enabled: false, Threshold: 10, Smart: true},
		Rotate:            0,
		Quality:           0,
		FormatQuality:     maps.Clone(config.FormatQuality),
		MaxBytes:          0,
		Format:            imagetype.Unknown,
		Background:        vips.Color{R: 255, G: 255, B: 255},
		Blur:              0,
		Sharpen:           0,
		Dpr:               1,
		Watermark:         WatermarkOptions{Opacity: 1, Position: GravityOptions{Type: GravityCenter}},
		StripMetadata:     config.StripMetadata,
		KeepCopyright:     config.KeepCopyright,
		StripColorProfile: config.StripColorProfile,
		AutoRotate:        config.AutoRotate,
		EnforceThumbnail:  config.EnforceThumbnail,
		ReturnAttachment:  config.ReturnAttachment,

		SkipProcessingFormats: slices.Clone(config.SkipProcessingFormats),

		SecurityOptions: security.NewOptions(),
	}

	return &po
}

func (po *ProcessingOptions) GetQuality() int {
	q := po.Quality

	if q == 0 {
		q = po.FormatQuality[po.Format]
	}

	if q == 0 {
		q = po.config.Quality
	}

	return q
}

func (po *ProcessingOptions) Diff() structdiff.Entries {
	return structdiff.Diff(po.defaultOptions, po)
}

func (po *ProcessingOptions) String() string {
	return po.Diff().String()
}

func (po *ProcessingOptions) MarshalJSON() ([]byte, error) {
	return po.Diff().MarshalJSON()
}

func (po *ProcessingOptions) LogValue() slog.Value {
	return po.Diff().LogValue()
}

// Default returns the ProcessingOptions instance with defaults set
func (po *ProcessingOptions) Default() *ProcessingOptions {
	return po.defaultOptions.clone()
}

// clone clones ProcessingOptions struct and its slices and maps
func (po *ProcessingOptions) clone() *ProcessingOptions {
	clone := *po

	clone.FormatQuality = maps.Clone(po.FormatQuality)
	clone.SkipProcessingFormats = slices.Clone(po.SkipProcessingFormats)
	clone.UsedPresets = slices.Clone(po.UsedPresets)

	if po.Expires != nil {
		poExipres := *po.Expires
		clone.Expires = &poExipres
	}

	// Copy the pointer to the default options struct from parent.
	// Nil means that we have just cloned the default options struct itself
	// so we set it as default options.
	if clone.defaultOptions == nil {
		clone.defaultOptions = po
	}

	return &clone
}

func (f *Factory) applyURLOption(po *ProcessingOptions, name string, args []string, usedPresets ...string) error {
	switch name {
	case "resize", "rs":
		return applyResizeOption(po, args)
	case "size", "s":
		return applySizeOption(po, args)
	case "resizing_type", "rt":
		return applyResizingTypeOption(po, args)
	case "width", "w":
		return applyWidthOption(po, args)
	case "height", "h":
		return applyHeightOption(po, args)
	case "min-width", "mw":
		return applyMinWidthOption(po, args)
	case "min-height", "mh":
		return applyMinHeightOption(po, args)
	case "zoom", "z":
		return applyZoomOption(po, args)
	case "dpr":
		return applyDprOption(po, args)
	case "enlarge", "el":
		return applyEnlargeOption(po, args)
	case "extend", "ex":
		return applyExtendOption(po, args)
	case "extend_aspect_ratio", "extend_ar", "exar":
		return applyExtendAspectRatioOption(po, args)
	case "gravity", "g":
		return applyGravityOption(po, args)
	case "crop", "c":
		return applyCropOption(po, args)
	case "trim", "t":
		return applyTrimOption(po, args)
	case "padding", "pd":
		return applyPaddingOption(po, args)
	case "auto_rotate", "ar":
		return applyAutoRotateOption(po, args)
	case "rotate", "rot":
		return applyRotateOption(po, args)
	case "background", "bg":
		return applyBackgroundOption(po, args)
	case "blur", "bl":
		return applyBlurOption(po, args)
	case "sharpen", "sh":
		return applySharpenOption(po, args)
	case "pixelate", "pix":
		return applyPixelateOption(po, args)
	case "watermark", "wm":
		return applyWatermarkOption(po, args)
	case "strip_metadata", "sm":
		return applyStripMetadataOption(po, args)
	case "keep_copyright", "kcr":
		return applyKeepCopyrightOption(po, args)
	case "strip_color_profile", "scp":
		return applyStripColorProfileOption(po, args)
	case "enforce_thumbnail", "eth":
		return applyEnforceThumbnailOption(po, args)
	// Saving options
	case "quality", "q":
		return applyQualityOption(po, args)
	case "format_quality", "fq":
		return applyFormatQualityOption(po, args)
	case "max_bytes", "mb":
		return applyMaxBytesOption(po, args)
	case "format", "f", "ext":
		return applyFormatOption(po, args)
	// Handling options
	case "skip_processing", "skp":
		return applySkipProcessingFormatsOption(po, args)
	case "raw":
		return applyRawOption(po, args)
	case "cachebuster", "cb":
		return applyCacheBusterOption(po, args)
	case "expires", "exp":
		return applyExpiresOption(po, args)
	case "filename", "fn":
		return applyFilenameOption(po, args)
	case "return_attachment", "att":
		return applyReturnAttachmentOption(po, args)
	// Presets
	case "preset", "pr":
		return applyPresetOption(f, po, args, usedPresets...)
	// Security
	case "max_src_resolution", "msr":
		return applyMaxSrcResolutionOption(po, args)
	case "max_src_file_size", "msfs":
		return applyMaxSrcFileSizeOption(po, args)
	case "max_animation_frames", "maf":
		return applyMaxAnimationFramesOption(po, args)
	case "max_animation_frame_resolution", "mafr":
		return applyMaxAnimationFrameResolutionOption(po, args)
	case "max_result_dimension", "mrd":
		return applyMaxResultDimensionOption(po, args)
	}

	return newUnknownOptionError("processing", name)
}

func (f *Factory) applyURLOptions(po *ProcessingOptions, options urlOptions, allowAll bool, usedPresets ...string) error {
	allowAll = allowAll || len(f.config.AllowedProcessingOptions) == 0

	for _, opt := range options {
		if !allowAll && !slices.Contains(f.config.AllowedProcessingOptions, opt.Name) {
			return newForbiddenOptionError("processing", opt.Name)
		}

		if err := f.applyURLOption(po, opt.Name, opt.Args, usedPresets...); err != nil {
			return err
		}
	}

	return nil
}

func (f *Factory) defaultProcessingOptions(headers http.Header) (*ProcessingOptions, error) {
	po := f.NewProcessingOptions()

	headerAccept := headers.Get("Accept")

	if strings.Contains(headerAccept, "image/webp") {
		po.PreferWebP = f.config.AutoWebp || f.config.EnforceWebp
		po.EnforceWebP = f.config.EnforceWebp
	}

	if strings.Contains(headerAccept, "image/avif") {
		po.PreferAvif = f.config.AutoAvif || f.config.EnforceAvif
		po.EnforceAvif = f.config.EnforceAvif
	}

	if strings.Contains(headerAccept, "image/jxl") {
		po.PreferJxl = f.config.AutoJxl || f.config.EnforceJxl
		po.EnforceJxl = f.config.EnforceJxl
	}

	if f.config.EnableClientHints {
		headerDPR := headers.Get("Sec-CH-DPR")
		if len(headerDPR) == 0 {
			headerDPR = headers.Get("DPR")
		}
		if len(headerDPR) > 0 {
			if dpr, err := strconv.ParseFloat(headerDPR, 64); err == nil && (dpr > 0 && dpr <= maxClientHintDPR) {
				po.Dpr = dpr
			}
		}

		headerWidth := headers.Get("Sec-CH-Width")
		if len(headerWidth) == 0 {
			headerWidth = headers.Get("Width")
		}
		if len(headerWidth) > 0 {
			if w, err := strconv.Atoi(headerWidth); err == nil {
				po.Width = imath.Shrink(w, po.Dpr)
			}
		}
	}

	if _, ok := f.presets["default"]; ok {
		if err := applyPresetOption(f, po, []string{"default"}); err != nil {
			return po, err
		}
	}

	return po, nil
}

// ParsePath parses the given request path and returns the processing options and image URL
func (f *Factory) ParsePath(
	path string,
	headers http.Header,
) (po *ProcessingOptions, imageURL string, err error) {
	if path == "" || path == "/" {
		return nil, "", newInvalidURLError("invalid path: %s", path)
	}

	parts := strings.Split(strings.TrimPrefix(path, "/"), "/")

	if f.config.OnlyPresets {
		po, imageURL, err = f.parsePathPresets(parts, headers)
	} else {
		po, imageURL, err = f.parsePathOptions(parts, headers)
	}

	if err != nil {
		return nil, "", ierrors.Wrap(err, 0)
	}

	return po, imageURL, nil
}

// parsePathOptions parses processing options from the URL path
func (f *Factory) parsePathOptions(parts []string, headers http.Header) (*ProcessingOptions, string, error) {
	if _, ok := resizeTypes[parts[0]]; ok {
		return nil, "", newInvalidURLError("It looks like you're using the deprecated basic URL format")
	}

	po, err := f.defaultProcessingOptions(headers)
	if err != nil {
		return nil, "", err
	}

	options, urlParts := f.parseURLOptions(parts)

	if err = f.applyURLOptions(po, options, false); err != nil {
		return nil, "", err
	}

	url, extension, err := f.DecodeURL(urlParts)
	if err != nil {
		return nil, "", err
	}

	if !po.Raw && len(extension) > 0 {
		if err = applyFormatOption(po, []string{extension}); err != nil {
			return nil, "", err
		}
	}

	return po, url, nil
}

// parsePathPresets parses presets from the URL path
func (f *Factory) parsePathPresets(parts []string, headers http.Header) (*ProcessingOptions, string, error) {
	po, err := f.defaultProcessingOptions(headers)
	if err != nil {
		return nil, "", err
	}

	presets := strings.Split(parts[0], f.config.ArgumentsSeparator)
	urlParts := parts[1:]

	if err = applyPresetOption(f, po, presets); err != nil {
		return nil, "", err
	}

	url, extension, err := f.DecodeURL(urlParts)
	if err != nil {
		return nil, "", err
	}

	if !po.Raw && len(extension) > 0 {
		if err = applyFormatOption(po, []string{extension}); err != nil {
			return nil, "", err
		}
	}

	return po, url, nil
}

func (po *ProcessingOptions) isSecurityOptionsAllowed() error {
	if po.config.AllowSecurityOptions {
		return nil
	}

	return newSecurityOptionsError()
}