package s3

import (
	"bytes"
	"fmt"
	"io"
	"os"
	"strconv"
	"time"

	"crypto/md5"
	"encoding/base64"
	"io/ioutil"
	"net/http"
)

/// Object API operations

// Put - upload new object to bucket
func (c *Client) Put(bucket, key string, size int64, contents io.Reader) error {
	req := newReq(c.keyURL(bucket, key))
	req.Method = "PUT"
	req.ContentLength = size

	h := md5.New()
	// Memory where data is present
	sink := new(bytes.Buffer)
	mw := io.MultiWriter(h, sink)
	written, err := io.Copy(mw, contents)
	if written != size {
		return fmt.Errorf("Data read mismatch")
	}
	if err != nil {
		return err
	}
	req.Body = ioutil.NopCloser(sink)
	b64 := base64.StdEncoding.EncodeToString(h.Sum(nil))
	req.Header.Set("Content-MD5", b64)
	c.Auth.signRequest(req)

	res, err := c.transport().RoundTrip(req)
	if res != nil && res.Body != nil {
		defer res.Body.Close()
	}

	if err != nil {
		return err
	}
	if res.StatusCode != http.StatusOK {
		// res.Write(os.Stderr)
		return fmt.Errorf("Got response code %d from s3", res.StatusCode)
	}
	return nil
}

// Stat - returns 0, "", os.ErrNotExist if not on S3
func (c *Client) Stat(key, bucket string) (size int64, date time.Time, reterr error) {
	req := newReq(c.keyURL(bucket, key))
	req.Method = "HEAD"
	c.Auth.signRequest(req)
	res, err := c.transport().RoundTrip(req)
	if res != nil && res.Body != nil {
		defer res.Body.Close()
	}
	if err != nil {
		return 0, date, err
	}

	switch res.StatusCode {
	case http.StatusNotFound:
		return 0, date, os.ErrNotExist
	case http.StatusOK:
		size, err = strconv.ParseInt(res.Header.Get("Content-Length"), 10, 64)
		if err != nil {
			return 0, date, err
		}
		if dateStr := res.Header.Get("Last-Modified"); dateStr != "" {
			// AWS S3 uses RFC1123 standard for Date in HTTP header, unlike XML content
			date, err := time.Parse(time.RFC1123, dateStr)
			if err != nil {
				return 0, date, err
			}
			return size, date, nil
		}
	default:
		return 0, date, fmt.Errorf("s3: Unexpected status code %d statting object %v", res.StatusCode, key)
	}
	return
}

// Get - download a requested object from a given bucket
func (c *Client) Get(bucket, key string) (body io.ReadCloser, size int64, err error) {
	req := newReq(c.keyURL(bucket, key))
	c.Auth.signRequest(req)
	res, err := c.transport().RoundTrip(req)
	if err != nil {
		return
	}
	switch res.StatusCode {
	case http.StatusOK:
		return res.Body, res.ContentLength, nil
	case http.StatusNotFound:
		res.Body.Close()
		return nil, 0, os.ErrNotExist
	default:
		res.Body.Close()
		return nil, 0, fmt.Errorf("Amazon HTTP error on GET: %d", res.StatusCode)
	}
}

// GetPartial fetches part of the s3 key object in bucket.
// If length is negative, the rest of the object is returned.
// The caller must close rc.
func (c *Client) GetPartial(bucket, key string, offset, length int64) (rc io.ReadCloser, err error) {
	if offset < 0 {
		return nil, fmt.Errorf("invalid negative length")
	}

	req := newReq(c.keyURL(bucket, key))
	if length >= 0 {
		req.Header.Set("Range", fmt.Sprintf("bytes=%d-%d", offset, offset+length-1))
	} else {
		req.Header.Set("Range", fmt.Sprintf("bytes=%d-", offset))
	}
	c.Auth.signRequest(req)

	res, err := c.transport().RoundTrip(req)
	if err != nil {
		return
	}
	switch res.StatusCode {
	case http.StatusOK, http.StatusPartialContent:
		return res.Body, nil
	case http.StatusNotFound:
		res.Body.Close()
		return nil, os.ErrNotExist
	default:
		res.Body.Close()
		return nil, fmt.Errorf("Amazon HTTP error on GET: %d", res.StatusCode)
	}
}