package proxy

import (
	"net/http"
	"net/http/httputil"
	"net/url"
	"strings"

	"github.com/owncloud/ocis-proxy/pkg/config"
)

// MultiHostReverseProxy extends httputil to support multiple hosts with diffent policies
type MultiHostReverseProxy struct {
	httputil.ReverseProxy
	Directors map[string]map[string]func(req *http.Request)
}

// NewMultiHostReverseProxy undocummented
func NewMultiHostReverseProxy(conf *config.Config) *MultiHostReverseProxy {
	reverseProxy := &MultiHostReverseProxy{Directors: make(map[string]map[string]func(req *http.Request))}

	for _, policy := range conf.Policies {
		for _, route := range policy.Routes {
			uri, err := url.Parse(route.Backend)
			if err != nil { /* do something with err */
			}
			reverseProxy.AddHost(policy.Name, uri, route.Endpoint)
		}
	}

	return reverseProxy
}

func singleJoiningSlash(a, b string) string {
	aslash := strings.HasSuffix(a, "/")
	bslash := strings.HasPrefix(b, "/")
	switch {
	case aslash && bslash:
		return a + b[1:]
	case !aslash && !bslash:
		return a + "/" + b
	}
	return a + b
}

// AddHost undocumented
func (p *MultiHostReverseProxy) AddHost(policy string, target *url.URL, endpoint string) {
	targetQuery := target.RawQuery
	if p.Directors[policy] == nil {
		p.Directors[policy] = make(map[string]func(req *http.Request))
	}
	p.Directors[policy][endpoint] = func(req *http.Request) {
		req.URL.Scheme = target.Scheme
		req.URL.Host = target.Host
		req.URL.Path = singleJoiningSlash(target.Path, req.URL.Path)
		if targetQuery == "" || req.URL.RawQuery == "" {
			req.URL.RawQuery = targetQuery + req.URL.RawQuery
		} else {
			req.URL.RawQuery = targetQuery + "&" + req.URL.RawQuery
		}
		if _, ok := req.Header["User-Agent"]; !ok {
			// explicitly disable User-Agent so it's not set to default value
			req.Header.Set("User-Agent", "")
		}
	}
}

func (p *MultiHostReverseProxy) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	// TODO need to fetch from the accounts service
	policy := "reva"
	var hit bool

	for k := range p.Directors[policy] {
		if strings.HasPrefix(r.URL.Path, k) && k != "/" {
			p.Director = p.Directors[policy][k]
			hit = true
		}
	}

	// override default director with root. If any
	if !hit && p.Directors[policy]["/"] != nil {
		p.Director = p.Directors[policy]["/"]
	}

	// Call upstream ServeHTTP
	p.ReverseProxy.ServeHTTP(w, r)
}