package client

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
)

var (
	defaultAPI = "https://openlibrary.org/api/books"
)

// Client
type Client struct {
	httpClient http.Client
	apipath    string
}

// NewClient returns a new Client struct using http.DefaultClient and default api path.
func NewClient() (*Client, error) {
	return &Client{
		apipath: defaultAPI,
	}, nil
}

// SetHTTPClient updates the httpClient on the client with a manually-configured one.
// If unset, the client will fall back to using http.DefaultClient.
func (c *Client) SetHTTPClient(h http.Client) {
	c.httpClient = h
}

// SetAPIPath updates the hostname and path to the API; the default is "https://openlibrary.org/api/books".
// If APIPath is set to an empty string, the client will fall back to the default option.
func (c *Client) SetAPIPath(p string) {
	c.apipath = p
}

// GetByISBN fetches details for a book based on its ISBN10 or ISBN13.
func (c *Client) GetByISBN(k string) (*BookDetails, error) {
	key := "ISBN:" + k
	return c.fetch(key)
}

// GetByOCLC fetches details for a book based on its WorldCat OCLC number.
func (c *Client) GetByOCLC(k string) (*BookDetails, error) {
	key := "OCLC:" + k
	return c.fetch(key)
}

// GetByLCCN fetches details for a book based on its Library of Congress Control Number.
func (c *Client) GetByLCCN(k string) (*BookDetails, error) {
	key := "LCCN:" + k
	return c.fetch(key)
}

// GetByOLID fetches details for a book based on its OpenLibrary ID number.
func (c *Client) GetByOLID(k string) (*BookDetails, error) {
	key := "OLID:" + k
	return c.fetch(key)
}

// GetByRawKey fetches details for a book based on an arbitrary key; this method is provided
// as a future-proof fallback in case the OpenLibrary API adds more "bibkey" request types in the future.
// Most users should use one of the other lookup functions.
func (c *Client) GetByRawKey(k string) (*BookDetails, error) {
	return c.fetch(k)
}

func (c *Client) fetch(key string) (*BookDetails, error) {
	path := c.apipath
	if path == "" {
		path = defaultAPI
	}

	resp, err := c.httpClient.Get(path + "?bibkeys=%s&jscmd=data&format=json")
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("received non-200 status code: %d", resp.StatusCode)
	}

	var result response
	b, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}
	if err = json.Unmarshal(b, &result); err != nil {
		return nil, err
	}

	details, ok := result[key]
	if !ok {
		return nil, fmt.Errorf("book not found")
	}

	return &details, nil
}