package blog

import (
	"arimelody-web/admin/core"
	"arimelody-web/admin/templates"
	"arimelody-web/controller"
	"arimelody-web/model"
	"fmt"
	"net/http"
	"os"
	"slices"
)

func Handler(app *model.AppState) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        mux := http.NewServeMux()

        mux.Handle("/blogs/{id}", serveBlogPost(app))
        mux.Handle("/blogs/", serveBlogIndex(app))

        mux.ServeHTTP(w, r)
    })
}

type (
    blogPostCollection struct {
        Year int
        Posts []*model.BlogPost
    }
)

func (c *blogPostCollection) Clone() blogPostCollection {
    return blogPostCollection{
        Year: c.Year,
        Posts: slices.Clone(c.Posts),
    }
}

func serveBlogIndex(app *model.AppState) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        session := r.Context().Value("session").(*model.Session)

        posts, err := controller.GetBlogPosts(app.DB, false, -1, 0)
        if err != nil {
			fmt.Fprintf(os.Stderr, "WARN: Failed to fetch blog posts: %v\n", err)
            http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
            return
        }

        collections := []*blogPostCollection{}
        collection := blogPostCollection{
            Posts: []*model.BlogPost{},
            Year: -1,
        }
        for i, post := range posts {
            if i == 0 {
                collection.Year = post.PublishDate.Year()
            }

            if post.PublishDate.Year() != collection.Year {
                clone := collection.Clone()
                collections = append(collections, &clone)
                collection = blogPostCollection{
                    Year: post.PublishDate.Year(),
                    Posts: []*model.BlogPost{},
                }
            }

            collection.Posts = append(collection.Posts, post)

            if i == len(posts) - 1 {
                collections = append(collections, &collection)
            }
        }

        type blogsData struct {
            core.AdminPageData
            TotalPosts int
            Collections []*blogPostCollection
        }

        err = templates.BlogsTemplate.Execute(w, blogsData{
            AdminPageData: core.AdminPageData{
                Path: r.URL.Path,
                Session: session,
            },
            TotalPosts: len(posts),
            Collections: collections,
        })
		if err != nil {
            fmt.Fprintf(os.Stderr, "WARN: Error rendering admin blog index: %v\n", err)
            http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
            return
		}
    })
}

func serveBlogPost(app *model.AppState) http.Handler {
    return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        session := r.Context().Value("session").(*model.Session)

        blogID := r.PathValue("id")

        post, err := controller.GetBlogPost(app.DB, blogID)
        if err != nil {
            fmt.Fprintf(os.Stderr, "WARN: Failed to fetch blog %s: %v\n", blogID, err)
            http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
            return
        }
        if post == nil {
            http.NotFound(w, r)
            return
        }

        type blogPostData struct {
            core.AdminPageData
            Post *model.BlogPost
        }

        err = templates.EditBlogTemplate.Execute(w, blogPostData{
            AdminPageData: core.AdminPageData{
                Path: r.URL.Path,
                Session: session,
            },
            Post: post,
        })
		if err != nil {
            fmt.Fprintf(os.Stderr, "WARN: Error rendering admin edit page for blog %s: %v\n", blogID, err)
            http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)
            return
		}
    })
}