package web

import (
	"embed"
	"fmt"
	"html/template"
	"io/fs"
	"net/http"
	"net/url"
	"path/filepath"
	"strconv"
	"strings"

	"github.com/go-chi/chi/v5"
	"github.com/squid/rcs/backend/internal/config"
	"github.com/squid/rcs/backend/internal/db"
	"github.com/squid/rcs/backend/internal/imgur"
)

const pageSize = 50

//go:embed templates/* static/*
var assets embed.FS

// UI serves the search Web UI.
type UI struct {
	cfg   config.Config
	store *db.Store
	imgur *imgur.Client
	tmpl  *template.Template
}

// New creates the Web UI.
func New(cfg config.Config, store *db.Store, imgurClient *imgur.Client) (*UI, error) {
	tmpl, err := template.New("").Funcs(template.FuncMap{
		"hasImgur": func(url string) bool { return strings.TrimSpace(url) != "" },
		"snippet": func(body string) string {
			body = strings.TrimSpace(body)
			if len(body) > 280 {
				return body[:280] + "…"
			}
			return body
		},
		"screenshotURL": func(path string) string {
			if path == "" {
				return ""
			}
			return "/screenshots/" + filepath.Base(path)
		},
		"pageURL": func(data pageData, page int) string {
			values := url.Values{}
			if data.Query != "" {
				values.Set("q", data.Query)
			}
			if data.User != "" {
				values.Set("user", data.User)
			}
			if page > 1 {
				values.Set("page", strconv.Itoa(page))
			}
			encoded := values.Encode()
			if encoded == "" {
				return "/"
			}
			return "/?" + encoded
		},
	}).ParseFS(assets, "templates/*.html")
	if err != nil {
		return nil, fmt.Errorf("parse templates: %w", err)
	}
	return &UI{cfg: cfg, store: store, imgur: imgurClient, tmpl: tmpl}, nil
}

// StaticHandler serves embedded CSS/JS.
func (u *UI) StaticHandler() http.Handler {
	sub, err := fs.Sub(assets, "static")
	if err != nil {
		return http.NotFoundHandler()
	}
	return http.StripPrefix("/static/", http.FileServer(http.FS(sub)))
}

type pageData struct {
	Query      string
	User       string
	Results    []db.SearchResult
	Error      string
	Flash      string
	ImgurOn    bool
	Page       int
	TotalPages int
	Total      int
	HasPrev    bool
	HasNext    bool
	PrevPage   int
	NextPage   int
}

func parsePage(raw string) int {
	page, err := strconv.Atoi(strings.TrimSpace(raw))
	if err != nil || page < 1 {
		return 1
	}
	return page
}

// HandleIndex renders search results.
func (u *UI) HandleIndex(w http.ResponseWriter, r *http.Request) {
	q := strings.TrimSpace(r.URL.Query().Get("q"))
	user := strings.TrimSpace(r.URL.Query().Get("user"))
	flash := strings.TrimSpace(r.URL.Query().Get("flash"))
	errMsg := strings.TrimSpace(r.URL.Query().Get("error"))
	page := parsePage(r.URL.Query().Get("page"))

	data := pageData{
		Query:   q,
		User:    user,
		Flash:   flash,
		Error:   errMsg,
		ImgurOn: u.imgur.Enabled(),
		Page:    page,
	}

	total, err := u.store.CountComments(r.Context(), q, user)
	if err != nil {
		data.Error = err.Error()
	} else {
		data.Total = total
		data.TotalPages = total / pageSize
		if total%pageSize != 0 {
			data.TotalPages++
		}
		if data.TotalPages == 0 {
			data.TotalPages = 1
		}
		if page > data.TotalPages {
			page = data.TotalPages
			data.Page = page
		}
		data.HasPrev = page > 1
		data.HasNext = page < data.TotalPages
		data.PrevPage = page - 1
		data.NextPage = page + 1

		offset := (page - 1) * pageSize
		results, err := u.store.SearchComments(r.Context(), q, user, pageSize, offset)
		if err != nil {
			data.Error = err.Error()
		} else {
			data.Results = results
		}
	}

	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	if err := u.tmpl.ExecuteTemplate(w, "index.html", data); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
	}
}

// HandleExport uploads a comment screenshot to Imgur (or returns existing URL).
func (u *UI) HandleExport(w http.ResponseWriter, r *http.Request) {
	id := chi.URLParam(r, "id")
	q := strings.TrimSpace(r.FormValue("q"))
	if q == "" {
		q = strings.TrimSpace(r.URL.Query().Get("q"))
	}
	user := strings.TrimSpace(r.FormValue("user"))
	if user == "" {
		user = strings.TrimSpace(r.URL.Query().Get("user"))
	}
	pageRaw := strings.TrimSpace(r.FormValue("page"))
	if pageRaw == "" {
		pageRaw = strings.TrimSpace(r.URL.Query().Get("page"))
	}
	page := parsePage(pageRaw)

	redirect := func(flash, errMsg string) {
		values := url.Values{}
		if q != "" {
			values.Set("q", q)
		}
		if user != "" {
			values.Set("user", user)
		}
		if page > 1 {
			values.Set("page", strconv.Itoa(page))
		}
		if flash != "" {
			values.Set("flash", flash)
		}
		if errMsg != "" {
			values.Set("error", errMsg)
		}
		target := "/"
		if encoded := values.Encode(); encoded != "" {
			target += "?" + encoded
		}
		http.Redirect(w, r, target, http.StatusSeeOther)
	}

	comment, err := u.store.GetCommentByRedditID(r.Context(), id)
	if err != nil {
		redirect("", err.Error())
		return
	}
	if comment == nil {
		redirect("", "comment not found")
		return
	}
	if comment.ImgurURL != "" {
		redirect("Already exported", "")
		return
	}
	if comment.ScreenshotPath == "" {
		redirect("", "no screenshot for this comment")
		return
	}

	absPath := comment.ScreenshotPath
	if !filepath.IsAbs(absPath) {
		absPath = filepath.Join(u.cfg.DataDir, absPath)
	}
	link, err := u.imgur.UploadFile(absPath)
	if err != nil {
		redirect("", err.Error())
		return
	}
	if err := u.store.SetImgurURL(r.Context(), id, link); err != nil {
		redirect("", err.Error())
		return
	}
	redirect("Exported to Imgur", "")
}