// SPDX-License-Identifier: AGPL-3.0-or-later

package handler

import (
	"errors"
	"log/slog"
	"net/http"
	"strconv"
	"strings"

	"kode.naiv.no/olemd/favoritter/internal/image"
	"kode.naiv.no/olemd/favoritter/internal/middleware"
	"kode.naiv.no/olemd/favoritter/internal/render"
	"kode.naiv.no/olemd/favoritter/internal/store"
)

const defaultPageSize = 24

// handleFaveList shows the current user's faves.
func (h *Handler) handleFaveList(w http.ResponseWriter, r *http.Request) {
	user := middleware.UserFromContext(r.Context())
	page := queryInt(r, "page", 1)
	offset := (page - 1) * defaultPageSize

	faves, total, err := h.deps.Faves.ListByUser(user.ID, defaultPageSize, offset)
	if err != nil {
		slog.Error("list faves error", "error", err)
		http.Error(w, "Internal error", http.StatusInternalServerError)
		return
	}

	// Load tags for each fave.
	if err := h.deps.Faves.LoadTags(faves); err != nil {
		slog.Error("load tags error", "error", err)
	}

	totalPages := (total + defaultPageSize - 1) / defaultPageSize

	h.deps.Renderer.Page(w, r, "fave_list", render.PageData{
		Title: "Mine favoritter",
		Data: map[string]any{
			"Faves":      faves,
			"Page":       page,
			"TotalPages": totalPages,
			"Total":      total,
		},
	})
}

// handleFaveNew shows the form for creating a new fave.
func (h *Handler) handleFaveNew(w http.ResponseWriter, r *http.Request) {
	user := middleware.UserFromContext(r.Context())

	h.deps.Renderer.Page(w, r, "fave_form", render.PageData{
		Title: "Ny favoritt",
		Data: map[string]any{
			"IsNew":          true,
			"DefaultPrivacy": user.DefaultFavePrivacy,
		},
	})
}

// handleFaveCreate processes the form for creating a new fave.
func (h *Handler) handleFaveCreate(w http.ResponseWriter, r *http.Request) {
	user := middleware.UserFromContext(r.Context())

	if err := r.ParseMultipartForm(h.deps.Config.MaxUploadSize); err != nil {
		h.flash(w, r, "fave_form", "Filen er for stor.", "error", map[string]any{"IsNew": true})
		return
	}

	description := strings.TrimSpace(r.FormValue("description"))
	url := strings.TrimSpace(r.FormValue("url"))
	privacy := r.FormValue("privacy")
	tagStr := r.FormValue("tags")

	if description == "" {
		h.flash(w, r, "fave_form", "Beskrivelse er påkrevd.", "error", map[string]any{
			"IsNew": true, "Description": description, "URL": url, "Tags": tagStr, "Privacy": privacy,
		})
		return
	}

	if privacy != "public" && privacy != "private" {
		privacy = user.DefaultFavePrivacy
	}

	// Handle image upload.
	var imagePath string
	file, header, err := r.FormFile("image")
	if err == nil {
		defer file.Close()
		result, err := image.Process(file, header, h.deps.Config.UploadDir)
		if err != nil {
			slog.Error("image process error", "error", err)
			h.flash(w, r, "fave_form", "Kunne ikke behandle bildet. Sjekk at filen er et gyldig bilde (JPEG, PNG, GIF eller WebP).", "error", map[string]any{
				"IsNew": true, "Description": description, "URL": url, "Tags": tagStr, "Privacy": privacy,
			})
			return
		}
		imagePath = result.Filename
	}

	// Create the fave.
	fave, err := h.deps.Faves.Create(user.ID, description, url, imagePath, privacy)
	if err != nil {
		slog.Error("create fave error", "error", err)
		h.flash(w, r, "fave_form", "Noe gikk galt. Prøv igjen.", "error", map[string]any{"IsNew": true})
		return
	}

	// Set tags.
	if tagStr != "" {
		tags := parseTags(tagStr)
		if err := h.deps.Tags.SetFaveTags(fave.ID, tags); err != nil {
			slog.Error("set tags error", "error", err)
		}
	}

	http.Redirect(w, r, h.deps.Config.BasePath+"/faves/"+strconv.FormatInt(fave.ID, 10), http.StatusSeeOther)
}

// handleFaveDetail shows a single fave.
func (h *Handler) handleFaveDetail(w http.ResponseWriter, r *http.Request) {
	id, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
	if err != nil {
		http.NotFound(w, r)
		return
	}

	fave, err := h.deps.Faves.GetByID(id)
	if err != nil {
		if errors.Is(err, store.ErrFaveNotFound) {
			http.NotFound(w, r)
			return
		}
		slog.Error("get fave error", "error", err)
		http.Error(w, "Internal error", http.StatusInternalServerError)
		return
	}

	// Check access: private faves are only visible to their owner.
	user := middleware.UserFromContext(r.Context())
	if fave.Privacy == "private" && (user == nil || user.ID != fave.UserID) {
		http.NotFound(w, r)
		return
	}

	// Load tags.
	tags, err := h.deps.Tags.ForFave(fave.ID)
	if err != nil {
		slog.Error("load tags error", "error", err)
	}
	fave.Tags = tags

	h.deps.Renderer.Page(w, r, "fave_detail", render.PageData{
		Title: fave.Description,
		Data: map[string]any{
			"Fave":    fave,
			"IsOwner": user != nil && user.ID == fave.UserID,
		},
	})
}

// handleFaveEdit shows the edit form for a fave.
func (h *Handler) handleFaveEdit(w http.ResponseWriter, r *http.Request) {
	user := middleware.UserFromContext(r.Context())

	id, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
	if err != nil {
		http.NotFound(w, r)
		return
	}

	fave, err := h.deps.Faves.GetByID(id)
	if err != nil {
		if errors.Is(err, store.ErrFaveNotFound) {
			http.NotFound(w, r)
			return
		}
		slog.Error("get fave error", "error", err)
		http.Error(w, "Internal error", http.StatusInternalServerError)
		return
	}

	// Only the owner can edit.
	if user.ID != fave.UserID {
		http.Error(w, "Forbidden", http.StatusForbidden)
		return
	}

	tags, _ := h.deps.Tags.ForFave(fave.ID)
	fave.Tags = tags

	tagNames := make([]string, len(tags))
	for i, t := range tags {
		tagNames[i] = t.Name
	}

	h.deps.Renderer.Page(w, r, "fave_form", render.PageData{
		Title: "Rediger favoritt",
		Data: map[string]any{
			"IsNew":       false,
			"Fave":        fave,
			"Description": fave.Description,
			"URL":         fave.URL,
			"Privacy":     fave.Privacy,
			"Tags":        strings.Join(tagNames, ", "),
		},
	})
}

// handleFaveUpdate processes the edit form.
func (h *Handler) handleFaveUpdate(w http.ResponseWriter, r *http.Request) {
	user := middleware.UserFromContext(r.Context())

	id, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
	if err != nil {
		http.NotFound(w, r)
		return
	}

	fave, err := h.deps.Faves.GetByID(id)
	if err != nil {
		if errors.Is(err, store.ErrFaveNotFound) {
			http.NotFound(w, r)
			return
		}
		slog.Error("get fave error", "error", err)
		http.Error(w, "Internal error", http.StatusInternalServerError)
		return
	}

	if user.ID != fave.UserID {
		http.Error(w, "Forbidden", http.StatusForbidden)
		return
	}

	if err := r.ParseMultipartForm(h.deps.Config.MaxUploadSize); err != nil {
		h.flash(w, r, "fave_form", "Filen er for stor.", "error", map[string]any{"IsNew": false, "Fave": fave})
		return
	}

	description := strings.TrimSpace(r.FormValue("description"))
	url := strings.TrimSpace(r.FormValue("url"))
	privacy := r.FormValue("privacy")
	tagStr := r.FormValue("tags")

	if description == "" {
		h.flash(w, r, "fave_form", "Beskrivelse er påkrevd.", "error", map[string]any{"IsNew": false, "Fave": fave})
		return
	}

	if privacy != "public" && privacy != "private" {
		privacy = fave.Privacy
	}

	// Handle image upload (optional on edit).
	imagePath := fave.ImagePath
	file, header, err := r.FormFile("image")
	if err == nil {
		defer file.Close()
		result, err := image.Process(file, header, h.deps.Config.UploadDir)
		if err != nil {
			slog.Error("image process error", "error", err)
			h.flash(w, r, "fave_form", "Kunne ikke behandle bildet. Sjekk at filen er et gyldig bilde (JPEG, PNG, GIF eller WebP).", "error", map[string]any{"IsNew": false, "Fave": fave})
			return
		}
		if fave.ImagePath != "" {
			if delErr := image.Delete(h.deps.Config.UploadDir, fave.ImagePath); delErr != nil {
				slog.Error("image delete error", "error", delErr)
			}
		}
		imagePath = result.Filename
	}

	// Check if user wants to remove the existing image.
	if r.FormValue("remove_image") == "1" && imagePath != "" {
		if delErr := image.Delete(h.deps.Config.UploadDir, imagePath); delErr != nil {
			slog.Error("image delete error", "error", delErr)
		}
		imagePath = ""
	}

	if err := h.deps.Faves.Update(id, description, url, imagePath, privacy); err != nil {
		slog.Error("update fave error", "error", err)
		h.flash(w, r, "fave_form", "Noe gikk galt. Prøv igjen.", "error", map[string]any{"IsNew": false, "Fave": fave})
		return
	}

	// Update tags.
	tags := parseTags(tagStr)
	if err := h.deps.Tags.SetFaveTags(id, tags); err != nil {
		slog.Error("set tags error", "error", err)
	}

	http.Redirect(w, r, h.deps.Config.BasePath+"/faves/"+strconv.FormatInt(id, 10), http.StatusSeeOther)
}

// handleFaveDelete deletes a fave.
func (h *Handler) handleFaveDelete(w http.ResponseWriter, r *http.Request) {
	user := middleware.UserFromContext(r.Context())

	id, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
	if err != nil {
		http.NotFound(w, r)
		return
	}

	fave, err := h.deps.Faves.GetByID(id)
	if err != nil {
		if errors.Is(err, store.ErrFaveNotFound) {
			http.NotFound(w, r)
			return
		}
		slog.Error("get fave error", "error", err)
		http.Error(w, "Internal error", http.StatusInternalServerError)
		return
	}

	if user.ID != fave.UserID {
		http.Error(w, "Forbidden", http.StatusForbidden)
		return
	}

	if fave.ImagePath != "" {
		if delErr := image.Delete(h.deps.Config.UploadDir, fave.ImagePath); delErr != nil {
			slog.Error("image delete error", "error", delErr)
		}
	}

	if err := h.deps.Faves.Delete(id); err != nil {
		slog.Error("delete fave error", "error", err)
		http.Error(w, "Internal error", http.StatusInternalServerError)
		return
	}

	// If this was an HTMX request, return empty (the element is removed).
	if r.Header.Get("HX-Request") == "true" {
		w.WriteHeader(http.StatusOK)
		return
	}

	http.Redirect(w, r, h.deps.Config.BasePath+"/faves", http.StatusSeeOther)
}

// handleTagSearch handles tag autocomplete HTMX requests.
func (h *Handler) handleTagSearch(w http.ResponseWriter, r *http.Request) {
	q := r.URL.Query().Get("q")
	tags, err := h.deps.Tags.Search(q, 10)
	if err != nil {
		slog.Error("tag search error", "error", err)
		w.WriteHeader(http.StatusInternalServerError)
		return
	}

	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	if err := h.deps.Renderer.Partial(w, "tag_suggestions", tags); err != nil {
		slog.Error("render tag suggestions error", "error", err)
	}
}

// handleTagBrowse shows all public faves with a given tag.
func (h *Handler) handleTagBrowse(w http.ResponseWriter, r *http.Request) {
	tagName := r.PathValue("name")
	page := queryInt(r, "page", 1)
	offset := (page - 1) * defaultPageSize

	faves, total, err := h.deps.Faves.ListByTag(tagName, defaultPageSize, offset)
	if err != nil {
		slog.Error("list by tag error", "error", err)
		http.Error(w, "Internal error", http.StatusInternalServerError)
		return
	}

	if err := h.deps.Faves.LoadTags(faves); err != nil {
		slog.Error("load tags error", "error", err)
	}

	totalPages := (total + defaultPageSize - 1) / defaultPageSize

	h.deps.Renderer.Page(w, r, "tag_browse", render.PageData{
		Title: "Merkelapp: " + tagName,
		Data: map[string]any{
			"TagName":    tagName,
			"Faves":      faves,
			"Page":       page,
			"TotalPages": totalPages,
			"Total":      total,
		},
	})
}

// parseTags splits a comma-separated tag string into individual tag names.
func parseTags(s string) []string {
	parts := strings.Split(s, ",")
	var tags []string
	for _, p := range parts {
		p = strings.TrimSpace(p)
		if p != "" {
			tags = append(tags, p)
		}
	}
	return tags
}

// queryInt parses an integer query parameter with a default.
func queryInt(r *http.Request, key string, fallback int) int {
	v := r.URL.Query().Get(key)
	n, err := strconv.Atoi(v)
	if err != nil || n < 1 {
		return fallback
	}
	return n
}