package main

import (
  "encoding/json"
  "fmt"
  "io"
  "net/http"
  "os"
  "strconv"
  "strings"
)

const PARAM_IDS = "ids"
const MAX_TERMS = 10

// ============================================================================
func efsPathForId(efsId int) string {
  config := getConfig()

  idStr := fmt.Sprintf("%010d", efsId)
  path := fmt.Sprintf("%s/%s/%s/%s/%s/%s.dat", config.efsBasePath, idStr[0:2], idStr[2:4], idStr[4:6], idStr[6:8], idStr)

  return path
}

func handler(w http.ResponseWriter, r *http.Request) {
  err := r.ParseForm()
  if nil != err {
    fmt.Fprintln(w, "ERROR!", err)
    return
  }

  action := strings.Split(r.URL.Path[1:], "/")[0]

  switch(action) {
  case "download":
    handleDownload(w, r)
  case "info":
    handleInfo(w, r)
  case "search":
    handleSearch(w, r)
  default:
    fmt.Fprintf(w, "Unrecognized request:  %s\n", r.URL.Path[1:])
    fmt.Fprintf(w, "id: %s\n", r.FormValue("id"))
  
    fmt.Fprintln(w, "URL: ", r.URL)
    fmt.Fprintln(w, "Query: ", r.URL.Query())
  }
}

/*
func handleApp(w http.ResponseWriter, r *http.Request) {
  fmt.Println("handleApp():", r.URL.Path)

  // Security check:  prevent walking up the directory
  pos := strings.Index(r.Url.Path, "../")
  if (-1) == pos {
    fmt.Fprintln(w, "Paths containing \"../\" are not permitted:", r.URL.Path)
    return
  }

  fileName := "../app" + r.URL.Path
  _, err := os.Stat(fileName)
  if nil != err { 
    fmt.Fprintln(w, "Failed to find file:", fileName, err)
    return
  }

  http.ServeFile(w, r, "../app/" + r.URL.Path[1:])
}
*/

func handleDownload(w http.ResponseWriter, r *http.Request) {
  path := r.URL.Path[1:]
  tok := strings.Split(path, "/")
  if 2 != len(tok)  {
    fmt.Fprintln(w, "Unexpected path for download:", path)
    return
  }
  efsId, err := strconv.Atoi(tok[1])
  if (nil != err) || (0 == efsId) {
    fmt.Fprintln(w, "Invalid id for download:", path, err)
    return
  }
  
  mimeType := queryMimeTypeByEfsId(efsId)
  if 0 == len(mimeType) {
    fmt.Fprintln(w, "No MIME type found for id:", efsId)
    return
  }

  efsPath := efsPathForId(efsId)

  var fd *os.File
  fd, err = os.Open(efsPath)
  if nil != err {
    fmt.Fprintln(w, "Failed to read file for id:", efsId, err)
    return
  }
  defer fd.Close()

  io.Copy(w, fd)
}

func handleInfo(w http.ResponseWriter, r *http.Request) {
  idParams := r.Form[PARAM_IDS]
  if 1 != len(idParams) {
    fmt.Fprintln(w, "ERROR!  Detected either zero or multiple ids= parameters.  Exactly one expected.")
    return 
  } 

  idParam := idParams[0]
  idStrings := strings.Split(idParam, ",")
  ids := make([]int, len(idStrings))
  var err error
  for i, v := range(idStrings) {
    ids[i], err = strconv.Atoi(v)
    if nil != err {
      ids[i] = 0
    }
  }

  books := queryBooksByIds(ids)

  var jsonValue []byte
  jsonValue, err = json.Marshal(books)
  if nil != err {
    fmt.Fprintln(w, "ERROR!", err)
  } else {
    w.Write(jsonValue)
  }
}

func handleSearch(w http.ResponseWriter, r *http.Request) {
  var err error
  fmt.Println("DEBUG:  handleSearch():  " + r.URL.Path)

  fields := []Field{Author, Title, Series}

  terms := make([]SearchTerm, len(fields))
  
  count := 0
  for _, fv := range(fields) {
    paramName := fv.String()
    paramValues := r.Form[paramName]
    for _, pv := range(paramValues) {
      fmt.Println("DEBUG:  handleSearch():  ", paramName, "=", pv)
      if count >= len(terms) {
        fmt.Printf("WARNING:  limit of %d search terms exceeded.  One or more terms ignored.", len(terms))
        break
      }
      terms[count] = SearchTerm{Attribute:fv, Text:pv}
      count++
    }
  }

  terms = terms[:count]

  ids := queryIds(terms)

  jsonValue, err := json.Marshal(ids)
  if nil != err {
    fmt.Fprintln(w, "ERROR!", err)
  } else {
    w.Write(jsonValue)
  }
}