package httpserver

import (
	"context"
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"
	"html/template"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/go-chi/chi/v5"

	"github.com/tim/md-hub-secure/apps/server/internal/docs"
)

type layoutData struct {
	Title        string
	WebEnabled   bool
	BodyClass    string
	BodyTemplate string
	Data         any
}

type indexData struct {
	Documents []docs.DocumentRecord
}

type documentData struct {
	Title string
	Path  string
	Tags  []string
	Hash  string
	HTML  template.HTML
}

type errorData struct {
	Status  int
	Message string
}

func (s *Server) handleIndex(w http.ResponseWriter, r *http.Request) {
	items, err := s.documents.ListDocuments(r.Context())
	if err != nil {
		s.renderError(w, r, http.StatusInternalServerError, err.Error())
		return
	}

	s.renderTemplate(w, http.StatusOK, "index.gohtml", layoutData{
		Title:        "MD Hub Secure",
		WebEnabled:   s.webEnabled,
		BodyClass:    "page-index",
		BodyTemplate: "index_content",
		Data: indexData{
			Documents: items,
		},
	})
}

func (s *Server) handleDocsIndexRedirect(w http.ResponseWriter, r *http.Request) {
	http.Redirect(w, r, "/", http.StatusFound)
}

func (s *Server) handleDocument(w http.ResponseWriter, r *http.Request) {
	pagePath := chi.URLParam(r, "*")
	page, err := s.documents.LoadPage(r.Context(), pagePath)
	if err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			s.renderError(w, r, http.StatusNotFound, "document not found")
			return
		}
		s.renderError(w, r, http.StatusInternalServerError, err.Error())
		return
	}

	s.renderTemplate(w, http.StatusOK, "document.gohtml", layoutData{
		Title:        page.Title,
		WebEnabled:   s.webEnabled,
		BodyClass:    "page-document",
		BodyTemplate: "document_content",
		Data: documentData{
			Title: page.Title,
			Path:  page.Path,
			Tags:  page.Tags,
			Hash:  page.Hash,
			HTML:  template.HTML(page.HTML),
		},
	})
}

func (s *Server) handleHealth(w http.ResponseWriter, r *http.Request) {
	ctx, cancel := context.WithTimeout(r.Context(), 2*time.Second)
	defer cancel()

	dbStatus := "ok"
	if err := s.repository.Ping(ctx); err != nil {
		dbStatus = err.Error()
	}

	contentStatus := "ok"
	if _, err := os.Stat(s.config.Content.StoreDir); err != nil {
		contentStatus = err.Error()
	}

	writeJSON(w, http.StatusOK, map[string]string{
		"status":       "ok",
		"database":     dbStatus,
		"contentStore": contentStatus,
	})
}

func (s *Server) handleUpload(w http.ResponseWriter, r *http.Request) {
	if err := r.ParseMultipartForm(32 << 20); err != nil {
		s.renderError(w, r, http.StatusBadRequest, "invalid multipart upload")
		return
	}

	file, header, err := r.FormFile("file")
	if err != nil {
		s.renderError(w, r, http.StatusBadRequest, "file field is required")
		return
	}
	defer file.Close()

	content, err := io.ReadAll(io.LimitReader(file, 32<<20))
	if err != nil {
		s.renderError(w, r, http.StatusInternalServerError, "read upload")
		return
	}

	contentType := http.DetectContentType(content)
	if !isAllowedContentType(contentType) {
		s.renderError(w, r, http.StatusBadRequest, "unsupported content type")
		return
	}

	record, err := s.contentStore.PutBytes(content)
	if err != nil {
		s.renderError(w, r, http.StatusInternalServerError, "store upload")
		return
	}

	if err := s.repository.SaveAttachment(r.Context(), docs.AttachmentRecord{
		Hash:         record.Hash,
		OriginalName: header.Filename,
		ContentType:  contentType,
		SizeBytes:    record.Size,
		CreatedAt:    time.Now().UTC(),
	}); err != nil {
		s.renderError(w, r, http.StatusInternalServerError, "persist upload metadata")
		return
	}

	writeJSONWithStatus(w, http.StatusCreated, map[string]string{
		"hash":          record.Hash,
		"contentType":   contentType,
		"attachmentUrl": "/attachments/" + record.Hash,
	})
}

func (s *Server) handleAttachment(w http.ResponseWriter, r *http.Request) {
	hash := chi.URLParam(r, "hash")
	attachment, err := s.repository.GetAttachment(r.Context(), hash)
	if err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			s.renderError(w, r, http.StatusNotFound, "attachment not found")
			return
		}
		s.renderError(w, r, http.StatusInternalServerError, "lookup attachment")
		return
	}

	content, err := s.contentStore.Read(hash)
	if err != nil {
		s.renderError(w, r, http.StatusInternalServerError, "read attachment")
		return
	}

	w.Header().Set("Content-Type", attachment.ContentType)
	w.Header().Set("Content-Disposition", fmt.Sprintf("inline; filename=%q", sanitizeFilename(attachment.OriginalName)))
	w.Header().Set("Content-Length", fmt.Sprintf("%d", len(content)))
	w.WriteHeader(http.StatusOK)
	_, _ = w.Write(content)
}

func (s *Server) renderTemplate(w http.ResponseWriter, status int, name string, data layoutData) {
	w.Header().Set("Content-Type", "text/html; charset=utf-8")
	w.WriteHeader(status)
	if err := s.templates.ExecuteTemplate(w, name, data); err != nil {
		http.Error(w, "template error", http.StatusInternalServerError)
	}
}

func (s *Server) renderError(w http.ResponseWriter, r *http.Request, status int, message string) {
	s.renderTemplate(w, status, "error.gohtml", layoutData{
		Title:        http.StatusText(status),
		WebEnabled:   s.webEnabled,
		BodyClass:    "page-error",
		BodyTemplate: "error_content",
		Data: errorData{
			Status:  status,
			Message: message,
		},
	})
}

func isAllowedContentType(contentType string) bool {
	allowed := []string{
		"image/png",
		"image/jpeg",
		"image/gif",
		"image/webp",
		"application/pdf",
		"text/plain; charset=utf-8",
	}
	for _, candidate := range allowed {
		if strings.EqualFold(candidate, contentType) {
			return true
		}
	}
	return false
}

func sanitizeFilename(name string) string {
	name = filepath.Base(name)
	return strings.ReplaceAll(name, "\"", "")
}

func writeJSON(w http.ResponseWriter, status int, payload any) {
	writeJSONWithStatus(w, status, payload)
}

func writeJSONWithStatus(w http.ResponseWriter, status int, payload any) {
	w.Header().Set("Content-Type", "application/json; charset=utf-8")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(payload)
}