// 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 provides template functions for working with resources.
package resources

import (
	"fmt"
	"path/filepath"
	"sync"

	"github.com/gohugoio/hugo/common/maps"
	"github.com/pkg/errors"

	"github.com/gohugoio/hugo/tpl/internal/resourcehelpers"

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

	"github.com/gohugoio/hugo/deps"
	"github.com/gohugoio/hugo/resources"
	"github.com/gohugoio/hugo/resources/resource"

	"github.com/gohugoio/hugo/resources/resource_factories/bundler"
	"github.com/gohugoio/hugo/resources/resource_factories/create"
	"github.com/gohugoio/hugo/resources/resource_transformers/babel"
	"github.com/gohugoio/hugo/resources/resource_transformers/integrity"
	"github.com/gohugoio/hugo/resources/resource_transformers/minifier"
	"github.com/gohugoio/hugo/resources/resource_transformers/postcss"
	"github.com/gohugoio/hugo/resources/resource_transformers/templates"
	"github.com/gohugoio/hugo/resources/resource_transformers/tocss/dartsass"
	"github.com/gohugoio/hugo/resources/resource_transformers/tocss/scss"

	"github.com/spf13/cast"
)

// New returns a new instance of the resources-namespaced template functions.
func New(deps *deps.Deps) (*Namespace, error) {
	if deps.ResourceSpec == nil {
		return &Namespace{}, nil
	}

	scssClient, err := scss.New(deps.BaseFs.Assets, deps.ResourceSpec)
	if err != nil {
		return nil, err
	}

	minifyClient, err := minifier.New(deps.ResourceSpec)
	if err != nil {
		return nil, err
	}

	return &Namespace{
		deps:              deps,
		scssClientLibSass: scssClient,
		createClient:      create.New(deps.ResourceSpec),
		bundlerClient:     bundler.New(deps.ResourceSpec),
		integrityClient:   integrity.New(deps.ResourceSpec),
		minifyClient:      minifyClient,
		postcssClient:     postcss.New(deps.ResourceSpec),
		templatesClient:   templates.New(deps.ResourceSpec, deps),
		babelClient:       babel.New(deps.ResourceSpec),
	}, nil
}

// Namespace provides template functions for the "resources" namespace.
type Namespace struct {
	deps *deps.Deps

	createClient      *create.Client
	bundlerClient     *bundler.Client
	scssClientLibSass *scss.Client
	integrityClient   *integrity.Client
	minifyClient      *minifier.Client
	postcssClient     *postcss.Client
	babelClient       *babel.Client
	templatesClient   *templates.Client

	// The Dart Client requires a os/exec process, so  only
	// create it if we really need it.
	// This is mostly to avoid creating one per site build test.
	scssClientDartSassInit sync.Once
	scssClientDartSass     *dartsass.Client
}

func (ns *Namespace) getscssClientDartSass() (*dartsass.Client, error) {
	var err error
	ns.scssClientDartSassInit.Do(func() {
		ns.scssClientDartSass, err = dartsass.New(ns.deps.BaseFs.Assets, ns.deps.ResourceSpec)
		if err != nil {
			return
		}
		ns.deps.BuildClosers.Add(ns.scssClientDartSass)

	})

	return ns.scssClientDartSass, err
}

// Get locates the filename given in Hugo's assets filesystem
// and creates a Resource object that can be used for further transformations.
func (ns *Namespace) Get(filename interface{}) (resource.Resource, error) {
	filenamestr, err := cast.ToStringE(filename)
	if err != nil {
		return nil, err
	}

	filenamestr = filepath.Clean(filenamestr)

	return ns.createClient.Get(filenamestr)
}

// GetMatch finds the first Resource matching the given pattern, or nil if none found.
//
// It looks for files in the assets file system.
//
// See Match for a more complete explanation about the rules used.
func (ns *Namespace) GetMatch(pattern interface{}) (resource.Resource, error) {
	patternStr, err := cast.ToStringE(pattern)
	if err != nil {
		return nil, err
	}

	return ns.createClient.GetMatch(patternStr)
}

// Match gets all resources matching the given base path prefix, e.g
// "*.png" will match all png files. The "*" does not match path delimiters (/),
// so if you organize your resources in sub-folders, you need to be explicit about it, e.g.:
// "images/*.png". To match any PNG image anywhere in the bundle you can do "**.png", and
// to match all PNG images below the images folder, use "images/**.jpg".
//
// The matching is case insensitive.
//
// Match matches by using the files name with path relative to the file system root
// with Unix style slashes (/) and no leading slash, e.g. "images/logo.png".
//
// See https://github.com/gobwas/glob for the full rules set.
//
// It looks for files in the assets file system.
//
// See Match for a more complete explanation about the rules used.
func (ns *Namespace) Match(pattern interface{}) (resource.Resources, error) {
	patternStr, err := cast.ToStringE(pattern)
	if err != nil {
		return nil, err
	}

	return ns.createClient.Match(patternStr)
}

// Concat concatenates a slice of Resource objects. These resources must
// (currently) be of the same Media Type.
func (ns *Namespace) Concat(targetPathIn interface{}, r interface{}) (resource.Resource, error) {
	targetPath, err := cast.ToStringE(targetPathIn)
	if err != nil {
		return nil, err
	}

	var rr resource.Resources

	switch v := r.(type) {
	case resource.Resources:
		rr = v
	case resource.ResourcesConverter:
		rr = v.ToResources()
	default:
		return nil, fmt.Errorf("slice %T not supported in concat", r)
	}

	if len(rr) == 0 {
		return nil, errors.New("must provide one or more Resource objects to concat")
	}

	return ns.bundlerClient.Concat(targetPath, rr)
}

// FromString creates a Resource from a string published to the relative target path.
func (ns *Namespace) FromString(targetPathIn, contentIn interface{}) (resource.Resource, error) {
	targetPath, err := cast.ToStringE(targetPathIn)
	if err != nil {
		return nil, err
	}
	content, err := cast.ToStringE(contentIn)
	if err != nil {
		return nil, err
	}

	return ns.createClient.FromString(targetPath, content)
}

// ExecuteAsTemplate creates a Resource from a Go template, parsed and executed with
// the given data, and published to the relative target path.
func (ns *Namespace) ExecuteAsTemplate(args ...interface{}) (resource.Resource, error) {
	if len(args) != 3 {
		return nil, fmt.Errorf("must provide targetPath, the template data context and a Resource object")
	}
	targetPath, err := cast.ToStringE(args[0])
	if err != nil {
		return nil, err
	}
	data := args[1]

	r, ok := args[2].(resources.ResourceTransformer)
	if !ok {
		return nil, fmt.Errorf("type %T not supported in Resource transformations", args[2])
	}

	return ns.templatesClient.ExecuteAsTemplate(r, targetPath, data)
}

// Fingerprint transforms the given Resource with a MD5 hash of the content in
// the RelPermalink and Permalink.
func (ns *Namespace) Fingerprint(args ...interface{}) (resource.Resource, error) {
	if len(args) < 1 || len(args) > 2 {
		return nil, errors.New("must provide a Resource and (optional) crypto algo")
	}

	var algo string
	resIdx := 0

	if len(args) == 2 {
		resIdx = 1
		var err error
		algo, err = cast.ToStringE(args[0])
		if err != nil {
			return nil, err
		}
	}

	r, ok := args[resIdx].(resources.ResourceTransformer)
	if !ok {
		return nil, fmt.Errorf("%T can not be transformed", args[resIdx])
	}

	return ns.integrityClient.Fingerprint(r, algo)
}

// Minify minifies the given Resource using the MediaType to pick the correct
// minifier.
func (ns *Namespace) Minify(r resources.ResourceTransformer) (resource.Resource, error) {
	return ns.minifyClient.Minify(r)
}

// ToCSS converts the given Resource to CSS. You can optional provide an Options
// object or a target path (string) as first argument.
func (ns *Namespace) ToCSS(args ...interface{}) (resource.Resource, error) {
	const (
		// Transpiler implementation can be controlled from the client by
		// setting the 'transpiler' option.
		// Default is currently 'libsass', but that may change.
		transpilerDart    = "dartsass"
		transpilerLibSass = "libsass"
	)

	var (
		r          resources.ResourceTransformer
		m          map[string]interface{}
		targetPath string
		err        error
		ok         bool
		transpiler = transpilerLibSass
	)

	r, targetPath, ok = resourcehelpers.ResolveIfFirstArgIsString(args)

	if !ok {
		r, m, err = resourcehelpers.ResolveArgs(args)
		if err != nil {
			return nil, err
		}
	}

	if m != nil {
		maps.PrepareParams(m)
		if t, found := m["transpiler"]; found {
			switch t {
			case transpilerDart, transpilerLibSass:
				transpiler = cast.ToString(t)
			default:
				return nil, errors.Errorf("unsupported transpiler %q; valid values are %q or %q", t, transpilerLibSass, transpilerDart)
			}
		}
	}

	if transpiler == transpilerLibSass {
		var options scss.Options
		if targetPath != "" {
			options.TargetPath = helpers.ToSlashTrimLeading(targetPath)
		} else if m != nil {
			options, err = scss.DecodeOptions(m)
			if err != nil {
				return nil, err
			}
		}

		return ns.scssClientLibSass.ToCSS(r, options)
	}

	if m == nil {
		m = make(map[string]interface{})
	}
	if targetPath != "" {
		m["targetPath"] = targetPath
	}

	client, err := ns.getscssClientDartSass()
	if err != nil {
		return nil, err
	}

	return client.ToCSS(r, m)

}

// PostCSS processes the given Resource with PostCSS
func (ns *Namespace) PostCSS(args ...interface{}) (resource.Resource, error) {
	r, m, err := resourcehelpers.ResolveArgs(args)
	if err != nil {
		return nil, err
	}
	var options postcss.Options
	if m != nil {
		options, err = postcss.DecodeOptions(m)
		if err != nil {
			return nil, err
		}
	}

	return ns.postcssClient.Process(r, options)
}

func (ns *Namespace) PostProcess(r resource.Resource) (postpub.PostPublishedResource, error) {
	return ns.deps.ResourceSpec.PostProcess(r)
}

// Babel processes the given Resource with Babel.
func (ns *Namespace) Babel(args ...interface{}) (resource.Resource, error) {
	r, m, err := resourcehelpers.ResolveArgs(args)
	if err != nil {
		return nil, err
	}
	var options babel.Options
	if m != nil {
		options, err = babel.DecodeOptions(m)

		if err != nil {
			return nil, err
		}
	}

	return ns.babelClient.Process(r, options)
}