package ofxgo

import (
	"errors"
	"io"
	"net/http"
	"strings"
)

// Client serves to aggregate OFX client settings that may be necessary to talk
// to a particular server due to quirks in that server's implementation.
// Client also provides the Request and RequestNoParse helper methods to aid in
// making and parsing requests.
type Client interface {
	// Used to fill out a Request object
	OfxVersion() ofxVersion
	ID() String
	Version() String
	IndentRequests() bool

	// Used to initiate requests to servers
	Request(r *Request) (*Response, error)
	RequestNoParse(r *Request) (*http.Response, error)
}

// BasicClient provides a standard Client implementation suitable for most
// financial institutions. BasicClient uses default, non-zero settings, even if
// its fields are not initialized.
type BasicClient struct {
	// Request fields to overwrite with the client's values. If nonempty,
	// defaults are used
	SpecVersion ofxVersion // VERSION in header
	AppID       string     // SONRQ>APPID
	AppVer      string     // SONRQ>APPVER

	// Don't insert newlines or indentation when marshalling to SGML/XML
	NoIndent bool
}

// OfxVersion returns the OFX specification version this BasicClient will marshal
// Requests as. Defaults to "203" if the client's SpecVersion field is empty.
func (c *BasicClient) OfxVersion() ofxVersion {
	if c.SpecVersion.Valid() {
		return c.SpecVersion
	}
	return OfxVersion203
}

// ID returns this BasicClient's OFX AppID field, defaulting to "OFXGO" if
// unspecified.
func (c *BasicClient) ID() String {
	if len(c.AppID) > 0 {
		return String(c.AppID)
	}
	return String("OFXGO")
}

// Version returns this BasicClient's version number as a string, defaulting to
// "0001" if unspecified.
func (c *BasicClient) Version() String {
	if len(c.AppVer) > 0 {
		return String(c.AppVer)
	}
	return String("0001")
}

// IndentRequests returns true if the marshaled XML should be indented (and
// contain newlines, since the two are linked in the current implementation)
func (c *BasicClient) IndentRequests() bool {
	return !c.NoIndent
}

// RawRequest is little more than a thin wrapper around http.Post
//
// In most cases, you should probably be using Request() instead, but
// RawRequest can be useful if you need to read the raw unparsed http response
// yourself (perhaps for downloading an OFX file for use by an external
// program, or debugging server behavior), or have a handcrafted request you'd
// like to try.
//
// Caveats: RawRequest does *not* take client settings into account as
// Client.Request() does, so your particular server may or may not like
// whatever we read from 'r'. The caller is responsible for closing the http
// Response.Body (see the http module's documentation for more information)
func RawRequest(URL string, r io.Reader) (*http.Response, error) {
	if !strings.HasPrefix(URL, "https://") {
		return nil, errors.New("Refusing to send OFX request with possible plain-text password over non-https protocol")
	}

	response, err := http.Post(URL, "application/x-ofx", r)
	if err != nil {
		return nil, err
	}

	if response.StatusCode != 200 {
		return nil, errors.New("OFXQuery request status: " + response.Status)
	}

	return response, nil
}

// rawRequestCookies is RawRequest with the added feature of sending cookies
func rawRequestCookies(URL string, r io.Reader, cookies []*http.Cookie) (*http.Response, error) {
	if !strings.HasPrefix(URL, "https://") {
		return nil, errors.New("Refusing to send OFX request with possible plain-text password over non-https protocol")
	}

	request, err := http.NewRequest("POST", URL, r)
	if err != nil {
		return nil, err
	}
	request.Header.Set("Content-Type", "application/x-ofx")
	for _, cookie := range cookies {
		request.AddCookie(cookie)
	}

	response, err := http.DefaultClient.Do(request)
	if err != nil {
		return nil, err
	}

	if response.StatusCode != 200 {
		return nil, errors.New("OFXQuery request status: " + response.Status)
	}

	return response, nil
}

// RequestNoParse marshals a Request object into XML, makes an HTTP request,
// and returns the raw HTTP response. Unlike RawRequest(), it takes client
// settings into account. Unlike Request(), it doesn't parse the response into
// an ofxgo.Request object.
//
// Caveat: The caller is responsible for closing the http Response.Body (see
// the http module's documentation for more information)
func (c *BasicClient) RequestNoParse(r *Request) (*http.Response, error) {
	r.SetClientFields(c)

	b, err := r.Marshal()
	if err != nil {
		return nil, err
	}

	response, err := RawRequest(r.URL, b)

	// Some financial institutions (cough, Vanguard, cough), require a cookie
	// to be set on the http request, or they return empty responses.
	// Fortunately, the initial response contains the cookie we need, so if we
	// detect an empty response with cookies set that didn't have any errors,
	// re-try the request while sending their cookies back to them.
	if err == nil && response.ContentLength <= 0 && len(response.Cookies()) > 0 {
		b, err = r.Marshal()
		if err != nil {
			return nil, err
		}

		return rawRequestCookies(r.URL, b, response.Cookies())
	}

	return response, err
}

// Request marshals a Request object into XML, makes an HTTP request against
// it's URL, and then unmarshals the response into a Response object.
//
// Before being marshaled, some of the the Request object's values are
// overwritten, namely those dictated by the BasicClient's configuration (Version,
// AppID, AppVer fields), and the client's current time (DtClient). These are
// updated in place in the supplied Request object so they may later be
// inspected by the caller.
func (c *BasicClient) Request(r *Request) (*Response, error) {
	response, err := c.RequestNoParse(r)
	if err != nil {
		return nil, err
	}
	defer response.Body.Close()

	ofxresp, err := ParseResponse(response.Body)
	if err != nil {
		return nil, err
	}
	return ofxresp, nil
}