/*

TODO:
Implement 'create'/'edit'/'read' modes with generic
configuration retrieved from OPTIONS request (using api.js)

'read' would use GET methods
'edit' would use PUT actions
'create' would use POST action

*/
const baseUrl = "http://localhost:8000/api"

/*
  Check that the response status is what's expected.
  Returns an object with :
    * success: bool
    * data: response data
*/
const processStatusCode = function(expected_code) {
  return function(response) {
    const status_code = response.status;
    let data;
    if (expected_code != 204) {
      data = response.json();
    } else {
      data = null
    }
    return Promise.all([status_code, data])
      .then(ret => ({
        success: ret[0] == expected_code,
        data: ret[1]
      }))
  }
}

/*
  Returns data on success or throw an error with data.
*/
const processSuccess = function(result) {
  if (!result.success) {
    throw result.data;
  }
  return result.data;
}

const _headers = {
  'Content-Type': 'application/json'
}
const _request = {
  get (url) {
    return fetch(
        url,
      { method: 'GET',
      })
      .then(processStatusCode(200))
      .then(processSuccess);
  },
  post (url, data) {
    return fetch(
        url,
      { method: 'POST',
        body: JSON.stringify(data),
        headers: _headers,
      })
      .then(processStatusCode(201))
      .then(processSuccess)
  },
  put (url, data) {
    return fetch(
        url,
      { method: 'PUT',
        body: JSON.stringify(data),
        headers: _headers,
      })
      .then(processStatusCode(200))
      .then(processSuccess)
  },
  delete(url) {
    return fetch(
      url,
    { method: 'DELETE',
      headers: _headers, })
      .then(processStatusCode(204))
      .then(processSuccess)
  },
  options (url) {
    return fetch(
      url,
    { method: 'OPTIONS',
    })
      .then(processStatusCode(200))
      .then(processSuccess)
  }
}

const mountEndPoint = function(url) {
  return {
    read (id) {
      return _request.get(url + id + '/')
    },
    create (data) {
      return _request.post(url, data)
    },
    edit (id, data) {
      return _request.put(url + id + '/', data)
    },
    delete (id) {
      return _request.delete(url + id + '/')
    },
    options() { return _request.options(url) },
    list () { return _request.get( url ) }
  }
}

const mountNestedEndPoint = function(url) {
  const getUrl = function(parent_id) {
    // TODO: Make it safe against url injection !
    return url.replace('*', parent_id)
  }
  return {
    read (parent_id, id) {
      return _request.get(getUrl(parent_id) + id + '/')
    },
    create (parent_id, data) {
      return _request.post(
        getUrl(parent_id),
        data,
        )
    },
    edit (parent_id, id, data) {
      return _request.put(
        getUrl(parent_id) + id + '/',
        data,
        )
    },
    delete (parent_id, id) {
      return _request.delete( getUrl(parent_id) + id + '/' )
    },
    options () {
      return _request.options( getUrl(1) )
    },
    list (parent_id) {
      return _request.get( getUrl(parent_id) )
    }
  }
}

export default {
  recipes: mountEndPoint(`${baseUrl}/recips/`),
  ingredients: mountNestedEndPoint(
    `${baseUrl}/recips/*/amounts/`
  ),
}