// Copyright 2019 The Hugo Authors. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package resources

import (
	"errors"
	"fmt"
	"mime"
	"os"
	"path"
	"path/filepath"
	"strings"
	"sync"

	"github.com/BurntSushi/locker"
	"github.com/gohugoio/hugo/config"
	"github.com/gohugoio/hugo/config/allconfig"
	"github.com/gohugoio/hugo/output"
	"github.com/gohugoio/hugo/resources/jsconfig"

	"github.com/gohugoio/hugo/common/herrors"
	"github.com/gohugoio/hugo/common/hexec"
	"github.com/gohugoio/hugo/common/loggers"

	"github.com/gohugoio/hugo/identity"

	"github.com/gohugoio/hugo/helpers"
	"github.com/gohugoio/hugo/hugofs"
	"github.com/gohugoio/hugo/resources/postpub"

	"github.com/gohugoio/hugo/cache/filecache"
	"github.com/gohugoio/hugo/media"
	"github.com/gohugoio/hugo/resources/images"
	"github.com/gohugoio/hugo/resources/page"
	"github.com/gohugoio/hugo/resources/resource"
	"github.com/gohugoio/hugo/tpl"
	"github.com/spf13/afero"
)

func NewSpec(
	s *helpers.PathSpec,
	common *SpecCommon, // may be nil
	imageCache *ImageCache, // may be nil
	incr identity.Incrementer,
	logger loggers.Logger,
	errorHandler herrors.ErrorSender,
	execHelper *hexec.Exec) (*Spec, error) {

	fileCaches, err := filecache.NewCaches(s)
	if err != nil {
		return nil, fmt.Errorf("failed to create file caches from configuration: %w", err)
	}

	conf := s.Cfg.GetConfig().(*allconfig.Config)
	imgConfig := conf.Imaging

	imaging, err := images.NewImageProcessor(imgConfig)
	if err != nil {
		return nil, err
	}

	if incr == nil {
		incr = &identity.IncrementByOne{}
	}

	if logger == nil {
		logger = loggers.NewDefault()
	}

	permalinks, err := page.NewPermalinkExpander(s.URLize, conf.Permalinks)
	if err != nil {
		return nil, err
	}

	if common == nil {
		common = &SpecCommon{
			incr:       incr,
			FileCaches: fileCaches,
			PostBuildAssets: &PostBuildAssets{
				PostProcessResources: make(map[string]postpub.PostPublishedResource),
				JSConfigBuilder:      jsconfig.NewBuilder(),
			},
			ResourceCache: &ResourceCache{
				fileCache: fileCaches.AssetsCache(),
				cache:     make(map[string]any),
				nlocker:   locker.NewLocker(),
			},
		}
	}

	if imageCache == nil {
		imageCache = newImageCache(
			fileCaches.ImageCache(),
			s,
		)
	} else {
		imageCache = imageCache.WithPathSpec(s)

	}

	rs := &Spec{
		PathSpec:    s,
		Logger:      logger,
		ErrorSender: errorHandler,
		imaging:     imaging,
		ImageCache:  imageCache,
		ExecHelper:  execHelper,

		Permalinks: permalinks,

		SpecCommon: common,
	}

	return rs, nil
}

type Spec struct {
	*helpers.PathSpec

	Logger      loggers.Logger
	ErrorSender herrors.ErrorSender

	TextTemplates tpl.TemplateParseFinder

	Permalinks page.PermalinkExpander

	ImageCache *ImageCache

	// Holds default filter settings etc.
	imaging *images.ImageProcessor

	ExecHelper *hexec.Exec

	*SpecCommon
}

// The parts of Spec that's comoon for all sites.
type SpecCommon struct {
	incr          identity.Incrementer
	ResourceCache *ResourceCache
	FileCaches    filecache.Caches

	// Assets used after the build is done.
	// This is shared between all sites.
	*PostBuildAssets
}

type PostBuildAssets struct {
	postProcessMu        sync.RWMutex
	PostProcessResources map[string]postpub.PostPublishedResource
	JSConfigBuilder      *jsconfig.Builder
}

func (r *Spec) New(fd ResourceSourceDescriptor) (resource.Resource, error) {
	return r.newResourceFor(fd)
}

func (r *Spec) MediaTypes() media.Types {
	return r.Cfg.GetConfigSection("mediaTypes").(media.Types)
}

func (r *Spec) OutputFormats() output.Formats {
	return r.Cfg.GetConfigSection("outputFormats").(output.Formats)
}

func (r *Spec) BuildConfig() config.BuildConfig {
	return r.Cfg.GetConfigSection("build").(config.BuildConfig)
}

func (r *Spec) CacheStats() string {
	r.ImageCache.mu.RLock()
	defer r.ImageCache.mu.RUnlock()

	s := fmt.Sprintf("Cache entries: %d", len(r.ImageCache.store))

	count := 0
	for k := range r.ImageCache.store {
		if count > 5 {
			break
		}
		s += "\n" + k
		count++
	}

	return s
}

func (r *Spec) ClearCaches() {
	r.ImageCache.clear()
	r.ResourceCache.clear()
}

func (r *Spec) DeleteBySubstring(s string) {
	r.ImageCache.deleteIfContains(s)
}

func (s *Spec) String() string {
	return "spec"
}

// TODO(bep) clean up below
func (r *Spec) newGenericResource(sourceFs afero.Fs,
	targetPathBuilder func() page.TargetPaths,
	osFileInfo os.FileInfo,
	sourceFilename,
	baseFilename string,
	mediaType media.Type) *genericResource {
	return r.newGenericResourceWithBase(
		sourceFs,
		nil,
		nil,
		targetPathBuilder,
		osFileInfo,
		sourceFilename,
		baseFilename,
		mediaType,
		nil,
	)
}

func (r *Spec) newGenericResourceWithBase(
	sourceFs afero.Fs,
	openReadSeekerCloser resource.OpenReadSeekCloser,
	targetPathBaseDirs []string,
	targetPathBuilder func() page.TargetPaths,
	osFileInfo os.FileInfo,
	sourceFilename,
	baseFilename string,
	mediaType media.Type,
	data map[string]any,
) *genericResource {
	if osFileInfo != nil && osFileInfo.IsDir() {
		panic(fmt.Sprintf("dirs not supported resource types: %v", osFileInfo))
	}

	// This value is used both to construct URLs and file paths, but start
	// with a Unix-styled path.
	baseFilename = helpers.ToSlashTrimLeading(baseFilename)
	fpath, fname := path.Split(baseFilename)

	resourceType := mediaType.MainType

	pathDescriptor := &resourcePathDescriptor{
		baseTargetPathDirs: helpers.UniqueStringsReuse(targetPathBaseDirs),
		targetPathBuilder:  targetPathBuilder,
		relTargetDirFile:   dirFile{dir: fpath, file: fname},
	}

	var fim hugofs.FileMetaInfo
	if osFileInfo != nil {
		fim = osFileInfo.(hugofs.FileMetaInfo)
	}

	gfi := &resourceFileInfo{
		fi:                   fim,
		openReadSeekerCloser: openReadSeekerCloser,
		sourceFs:             sourceFs,
		sourceFilename:       sourceFilename,
		h:                    &resourceHash{},
	}

	g := &genericResource{
		resourceFileInfo:       gfi,
		resourcePathDescriptor: pathDescriptor,
		mediaType:              mediaType,
		resourceType:           resourceType,
		spec:                   r,
		params:                 make(map[string]any),
		name:                   baseFilename,
		title:                  baseFilename,
		resourceContent:        &resourceContent{},
		data:                   data,
	}

	return g
}

func (r *Spec) newResource(sourceFs afero.Fs, fd ResourceSourceDescriptor) (resource.Resource, error) {
	fi := fd.FileInfo
	var sourceFilename string

	if fd.OpenReadSeekCloser != nil {
	} else if fd.SourceFilename != "" {
		var err error
		fi, err = sourceFs.Stat(fd.SourceFilename)
		if err != nil {
			if herrors.IsNotExist(err) {
				return nil, nil
			}
			return nil, err
		}
		sourceFilename = fd.SourceFilename
	} else {
		sourceFilename = fd.SourceFile.Filename()
	}

	if fd.RelTargetFilename == "" {
		fd.RelTargetFilename = sourceFilename
	}

	mimeType := fd.MediaType
	if mimeType.IsZero() {
		ext := strings.ToLower(filepath.Ext(fd.RelTargetFilename))
		var (
			found      bool
			suffixInfo media.SuffixInfo
		)
		mimeType, suffixInfo, found = r.MediaTypes().GetFirstBySuffix(strings.TrimPrefix(ext, "."))
		// TODO(bep) we need to handle these ambiguous types better, but in this context
		// we most likely want the application/xml type.
		if suffixInfo.Suffix == "xml" && mimeType.SubType == "rss" {
			mimeType, found = r.MediaTypes().GetByType("application/xml")
		}

		if !found {
			// A fallback. Note that mime.TypeByExtension is slow by Hugo standards,
			// so we should configure media types to avoid this lookup for most
			// situations.
			mimeStr := mime.TypeByExtension(ext)
			if mimeStr != "" {
				mimeType, _ = media.FromStringAndExt(mimeStr, ext)
			}
		}
	}

	gr := r.newGenericResourceWithBase(
		sourceFs,
		fd.OpenReadSeekCloser,
		fd.TargetBasePaths,
		fd.TargetPaths,
		fi,
		sourceFilename,
		fd.RelTargetFilename,
		mimeType,
		fd.Data)

	if mimeType.MainType == "image" {
		imgFormat, ok := images.ImageFormatFromMediaSubType(mimeType.SubType)
		if ok {
			ir := &imageResource{
				Image:        images.NewImage(imgFormat, r.imaging, nil, gr),
				baseResource: gr,
			}
			ir.root = ir
			return newResourceAdapter(gr.spec, fd.LazyPublish, ir), nil
		}
	}

	return newResourceAdapter(gr.spec, fd.LazyPublish, gr), nil
}

func (r *Spec) newResourceFor(fd ResourceSourceDescriptor) (resource.Resource, error) {
	if fd.OpenReadSeekCloser == nil {
		if fd.SourceFile != nil && fd.SourceFilename != "" {
			return nil, errors.New("both SourceFile and AbsSourceFilename provided")
		} else if fd.SourceFile == nil && fd.SourceFilename == "" {
			return nil, errors.New("either SourceFile or AbsSourceFilename must be provided")
		}
	}

	if fd.RelTargetFilename == "" {
		fd.RelTargetFilename = fd.Filename()
	}

	if len(fd.TargetBasePaths) == 0 {
		// If not set, we publish the same resource to all hosts.
		fd.TargetBasePaths = r.MultihostTargetBasePaths
	}

	return r.newResource(fd.Fs, fd)
}