// Copyright 2017-present 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 tplimpl

import (
	"fmt"
	"html/template"
	"strings"
	texttemplate "text/template"

	bp "github.com/spf13/hugo/bufferpool"
	"github.com/spf13/hugo/deps"
	"github.com/spf13/hugo/tpl/collections"
	"github.com/spf13/hugo/tpl/crypto"
	"github.com/spf13/hugo/tpl/data"
	"github.com/spf13/hugo/tpl/encoding"
	"github.com/spf13/hugo/tpl/images"
	"github.com/spf13/hugo/tpl/inflect"
	"github.com/spf13/hugo/tpl/os"
	"github.com/spf13/hugo/tpl/safe"
	hstrings "github.com/spf13/hugo/tpl/strings"
	"github.com/spf13/hugo/tpl/time"
	"github.com/spf13/hugo/tpl/transform"
	"github.com/spf13/hugo/tpl/urls"
)

// Some of the template funcs are'nt entirely stateless.
type templateFuncster struct {
	funcMap        template.FuncMap
	cachedPartials partialCache

	// Namespaces
	collections *collections.Namespace
	crypto      *crypto.Namespace
	data        *data.Namespace
	encoding    *encoding.Namespace
	images      *images.Namespace
	inflect     *inflect.Namespace
	os          *os.Namespace
	safe        *safe.Namespace
	strings     *hstrings.Namespace
	time        *time.Namespace
	transform   *transform.Namespace
	urls        *urls.Namespace

	*deps.Deps
}

func newTemplateFuncster(deps *deps.Deps) *templateFuncster {
	return &templateFuncster{
		Deps:           deps,
		cachedPartials: partialCache{p: make(map[string]interface{})},

		// Namespaces
		collections: collections.New(deps),
		crypto:      crypto.New(),
		data:        data.New(deps),
		encoding:    encoding.New(),
		images:      images.New(deps),
		inflect:     inflect.New(),
		os:          os.New(deps),
		safe:        safe.New(),
		strings:     hstrings.New(deps),
		time:        time.New(),
		transform:   transform.New(deps),
		urls:        urls.New(deps),
	}
}

// Partial executes the named partial and returns either a string,
// when called from text/template, for or a template.HTML.
func (t *templateFuncster) partial(name string, contextList ...interface{}) (interface{}, error) {
	if strings.HasPrefix("partials/", name) {
		name = name[8:]
	}
	var context interface{}

	if len(contextList) == 0 {
		context = nil
	} else {
		context = contextList[0]
	}

	for _, n := range []string{"partials/" + name, "theme/partials/" + name} {
		templ := t.Tmpl.Lookup(n)
		if templ == nil {
			// For legacy reasons.
			templ = t.Tmpl.Lookup(n + ".html")
		}
		if templ != nil {
			b := bp.GetBuffer()
			defer bp.PutBuffer(b)

			if err := templ.Execute(b, context); err != nil {
				return "", err
			}

			if _, ok := templ.Template.(*texttemplate.Template); ok {
				return b.String(), nil
			}

			return template.HTML(b.String()), nil

		}
	}

	return "", fmt.Errorf("Partial %q not found", name)
}