// Package handlers provides HTTP handlers for the file system.
package handlers

import (
	"errors"
	"fmt"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"time"

	"git.max-richter.dev/max/marka/parser"
	"git.max-richter.dev/max/marka/server/internal/fsx"
	"git.max-richter.dev/max/marka/server/internal/httpx"
)

type File struct{ root string }

func NewFile(root string) http.Handler { return &File{root: root} }

func (h *File) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	reqPath := r.URL.Path
	if reqPath == "" {
		reqPath = "/"
	}
	cleanRel, err := fsx.SafeRel(h.root, reqPath)
	if err != nil {
		httpx.WriteError(w, http.StatusBadRequest, err)
		return
	}
	target := filepath.Join(h.root, filepath.FromSlash(cleanRel))

	switch r.Method {
	case http.MethodGet:
		h.get(w, r, target)
	case http.MethodPost:
		h.post(w, r, target)
	default:
		httpx.WriteError(w, http.StatusMethodNotAllowed, errors.New("method not allowed"))
	}
}

func read(path string) any {
	data, err := os.ReadFile(path)
	if err != nil {
		return nil
	}
	res, err := parser.ParseFile(string(data))
	if err != nil {
		return nil
	}

	return res
}

func (h *File) get(w http.ResponseWriter, r *http.Request, target string) {
	fi, err := os.Stat(target)
	if err != nil {
		if os.IsNotExist(err) {
			httpx.WriteError(w, http.StatusNotFound, errors.New("not found"))
		} else {
			httpx.WriteError(w, http.StatusInternalServerError, err)
		}
		return
	}

	if fi.IsDir() {
		entries, err := os.ReadDir(target)
		if err != nil {
			httpx.WriteError(w, http.StatusInternalServerError, err)
			return
		}
		type item struct {
			Name    string    `json:"name"`
			Path    string    `json:"path"`
			Content any       `json:"content"`
			IsDir   bool      `json:"isDir"`
			Size    int64     `json:"size"`
			ModTime time.Time `json:"modTime"`
		}
		out := make([]item, 0, len(entries))
		for _, e := range entries {
			info, _ := e.Info()
			out = append(out, item{
				Name:    e.Name(),
				Path:    fsx.ResponsePath(h.root, filepath.Join(target, e.Name())),
				IsDir:   e.IsDir(),
				Content: read(filepath.Join(target, e.Name())),
				Size:    sizeOrZero(info),
				ModTime: modTimeOrZero(info),
			})
		}
		httpx.WriteJSON(w, http.StatusOK, out)
		return
	}

	f, err := os.Open(target)
	if err != nil {
		httpx.WriteError(w, http.StatusInternalServerError, err)
		return
	}
	defer f.Close()

	contentType := fsx.ContentTypeFor(target)

	if contentType == "application/markdown" {
		data, err := io.ReadAll(f)
		if err != nil {
			httpx.WriteError(w, http.StatusInternalServerError, err)
			return
		}
		res, err := parser.ParseFile(string(data))
		if err != nil {
			fmt.Println(err)
		}
		w.Header().Set("Content-Type", "application/json")
		httpx.WriteJSON(w, http.StatusOK, res)
		return
	}

	w.Header().Set("Content-Type", contentType)
	http.ServeContent(w, r, filepath.Base(target), fi.ModTime(), f)
}

func (h *File) post(w http.ResponseWriter, r *http.Request, target string) {
	if err := os.MkdirAll(filepath.Dir(target), 0o755); err != nil {
		httpx.WriteError(w, http.StatusInternalServerError, err)
		return
	}
	tmp := target + ".tmp~"
	f, err := os.Create(tmp)
	if err != nil {
		httpx.WriteError(w, http.StatusInternalServerError, err)
		return
	}

	if _, err := io.Copy(f, r.Body); err != nil {
		_ = f.Close()
		_ = os.Remove(tmp)
		httpx.WriteError(w, http.StatusInternalServerError, err)
		return
	}
	if err := f.Close(); err != nil {
		_ = os.Remove(tmp)
		httpx.WriteError(w, http.StatusInternalServerError, err)
		return
	}
	if err := os.Rename(tmp, target); err != nil {
		_ = os.Remove(tmp)
		httpx.WriteError(w, http.StatusInternalServerError, err)
		return
	}

	w.Header().Set("Location", r.URL.Path)
	w.WriteHeader(http.StatusCreated)
}

func sizeOrZero(fi os.FileInfo) int64 {
	if fi == nil {
		return 0
	}
	return fi.Size()
}

func modTimeOrZero(fi os.FileInfo) time.Time {
	if fi == nil {
		return time.Time{}
	}
	return fi.ModTime()
}