// Copyright 2016 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 hugolib

import (
	"path"
	"path/filepath"

	"github.com/gohugoio/hugo/cache"
)

// PageCollections contains the page collections for a site.
type PageCollections struct {
	// Includes only pages of all types, and only pages in the current language.
	Pages Pages

	// Includes all pages in all languages, including the current one.
	// Includes pages of all types.
	AllPages Pages

	// A convenience cache for the traditional index types, taxonomies, home page etc.
	// This is for the current language only.
	indexPages Pages

	// A convenience cache for the regular pages.
	// This is for the current language only.
	RegularPages Pages

	// A convenience cache for the all the regular pages.
	AllRegularPages Pages

	// Includes absolute all pages (of all types), including drafts etc.
	rawAllPages Pages

	pageCache *cache.PartitionedLazyCache
}

func (c *PageCollections) refreshPageCaches() {
	c.indexPages = c.findPagesByKindNotIn(KindPage, c.Pages)
	c.RegularPages = c.findPagesByKindIn(KindPage, c.Pages)
	c.AllRegularPages = c.findPagesByKindIn(KindPage, c.AllPages)

	var s *Site

	if len(c.Pages) > 0 {
		s = c.Pages[0].s
	}

	cacheLoader := func(kind string) func() (map[string]interface{}, error) {
		return func() (map[string]interface{}, error) {
			cache := make(map[string]interface{})
			switch kind {
			case KindPage:
				// Note that we deliberately use the pages from all sites
				// in this cache, as we intend to use this in the ref and relref
				// shortcodes. If the user says "sect/doc1.en.md", he/she knows
				// what he/she is looking for.
				for _, p := range c.AllRegularPages {
					cache[filepath.ToSlash(p.Source.Path())] = p
					// Ref/Relref supports this potentially ambiguous lookup.
					cache[p.Source.LogicalName()] = p

					if s != nil && p.s == s {
						// We need a way to get to the current language version.
						pathWithNoExtensions := path.Join(filepath.ToSlash(p.Source.Dir()), p.Source.TranslationBaseName())
						cache[pathWithNoExtensions] = p
					}

				}
			default:
				for _, p := range c.indexPages {
					key := path.Join(p.sections...)
					cache[key] = p
				}
			}

			return cache, nil
		}
	}

	partitions := make([]cache.Partition, len(allKindsInPages))

	for i, kind := range allKindsInPages {
		partitions[i] = cache.Partition{Key: kind, Load: cacheLoader(kind)}
	}

	c.pageCache = cache.NewPartitionedLazyCache(partitions...)
}

func newPageCollections() *PageCollections {
	return &PageCollections{}
}

func newPageCollectionsFromPages(pages Pages) *PageCollections {
	return &PageCollections{rawAllPages: pages}
}

func (c *PageCollections) getPage(typ string, sections ...string) *Page {
	var key string
	if len(sections) == 1 {
		key = filepath.ToSlash(sections[0])
	} else {
		key = path.Join(sections...)
	}

	p, _ := c.pageCache.Get(typ, key)
	if p == nil {
		return nil
	}
	return p.(*Page)

}

func (*PageCollections) findPagesByKindIn(kind string, inPages Pages) Pages {
	var pages Pages
	for _, p := range inPages {
		if p.Kind == kind {
			pages = append(pages, p)
		}
	}
	return pages
}

func (*PageCollections) findPagesByKindNotIn(kind string, inPages Pages) Pages {
	var pages Pages
	for _, p := range inPages {
		if p.Kind != kind {
			pages = append(pages, p)
		}
	}
	return pages
}

func (c *PageCollections) findPagesByKind(kind string) Pages {
	return c.findPagesByKindIn(kind, c.Pages)
}

func (c *PageCollections) addPage(page *Page) {
	c.rawAllPages = append(c.rawAllPages, page)
}

// When we get a REMOVE event we're not always getting all the individual files,
// so we need to remove all below a given path.
func (c *PageCollections) removePageByPathPrefix(path string) {
	for {
		i := c.rawAllPages.findFirstPagePosByFilePathPrefix(path)
		if i == -1 {
			break
		}
		c.rawAllPages = append(c.rawAllPages[:i], c.rawAllPages[i+1:]...)
	}
}

func (c *PageCollections) removePageByPath(path string) {
	if i := c.rawAllPages.findPagePosByFilePath(path); i >= 0 {
		c.clearResourceCacheForPage(c.rawAllPages[i])
		c.rawAllPages = append(c.rawAllPages[:i], c.rawAllPages[i+1:]...)
	}

}

func (c *PageCollections) removePage(page *Page) {
	if i := c.rawAllPages.findPagePos(page); i >= 0 {
		c.clearResourceCacheForPage(c.rawAllPages[i])
		c.rawAllPages = append(c.rawAllPages[:i], c.rawAllPages[i+1:]...)
	}

}

func (c *PageCollections) findPagesByShortcode(shortcode string) Pages {
	var pages Pages

	for _, p := range c.rawAllPages {
		if p.shortcodeState != nil {
			if _, ok := p.shortcodeState.nameSet[shortcode]; ok {
				pages = append(pages, p)
			}
		}
	}
	return pages
}

func (c *PageCollections) replacePage(page *Page) {
	// will find existing page that matches filepath and remove it
	c.removePage(page)
	c.addPage(page)
}

func (c *PageCollections) clearResourceCacheForPage(page *Page) {
	if len(page.Resources) > 0 {
		first := page.Resources[0]
		dir := path.Dir(first.RelPermalink())
		// This is done to keep the memory usage in check when doing live reloads.
		page.s.resourceSpec.DeleteCacheByPrefix(dir)
	}
}