package eduvpn

import (
	"fmt"
)

type DiscoFileError struct {
	URL string
	Err error
}

func (e *DiscoFileError) Error() string {
	return fmt.Sprintf("failed obtaining disco file %s with error %v", e.URL, e.Err)
}

type DiscoSigFileError struct {
	URL string
	Err error
}

func (e *DiscoSigFileError) Error() string {
	return fmt.Sprintf("failed obtaining disco signature file %s with error %v", e.URL, e.Err)
}

type DiscoVerifyError struct {
	File    string
	Sigfile string
	Err     error
}

func (e *DiscoVerifyError) Error() string {
	return fmt.Sprintf("failed verifying file %s with signature %s due to error %v", e.File, e.Sigfile, e.Err)
}

type DiscoList struct {
	Organizations *string `json:"organizations"`
	Servers       *string `json:"servers"`
}

// Helper function that gets a disco json
func getDiscoFile(jsonFile string) (string, error) {
	// Get json data
	discoURL := "https://disco.eduvpn.org/v2/"
	fileURL := discoURL + jsonFile
	_, fileBody, fileErr := HTTPGet(fileURL)

	if fileErr != nil {
		return "", &DiscoFileError{fileURL, fileErr}
	}

	// Get signature
	sigFile := jsonFile + ".minisig"
	sigURL := discoURL + sigFile
	_, sigBody, sigFileErr := HTTPGet(sigURL)

	if sigFileErr != nil {
		return "", &DiscoSigFileError{URL: sigURL, Err: sigFileErr}
	}

	// Verify signature
	// TODO: Handle this by keeping track of the previous sign time
	// Wrappers must do this?
	var previousSigTime uint64 = 0
	forcePrehash := false
	verifySuccess, verifyErr := Verify(string(sigBody), fileBody, jsonFile, previousSigTime, forcePrehash)

	if !verifySuccess || verifyErr != nil {
		return "", &DiscoVerifyError{File: jsonFile, Sigfile: sigFile, Err: verifyErr}
	}

	return string(fileBody), nil
}

type GetListError struct {
	File string
	Err  error
}

func (e *GetListError) Error() string {
	return fmt.Sprintf("failed getting disco list file %s with error %v", e.File, e.Err)
}

// FIXME: Implement these properly based on version and time info
func (eduvpn *VPNState) DetermineOrganizationsUpdate() bool {
	return eduvpn.DiscoList == nil || eduvpn.DiscoList.Organizations == nil
}

func (eduvpn *VPNState) DetermineServersUpdate() bool {
	return eduvpn.DiscoList == nil || eduvpn.DiscoList.Servers == nil
}

func (eduvpn *VPNState) EnsureDisco() {
	if eduvpn.DiscoList == nil {
		eduvpn.DiscoList = &DiscoList{}
	}
}

// Get the organization list
func (eduvpn *VPNState) GetOrganizationsList() (string, error) {
	if !eduvpn.DetermineOrganizationsUpdate() {
		return *eduvpn.DiscoList.Organizations, nil
	}
	file := "organization_list.json"
	body, err := getDiscoFile(file)
	if err != nil {
		return "", &GetListError{File: file, Err: err}
	}
	eduvpn.EnsureDisco()
	eduvpn.DiscoList.Organizations = &body
	return body, nil
}

// Get the server list
func (eduvpn *VPNState) GetServersList() (string, error) {
	if !eduvpn.DetermineServersUpdate() {
		return *eduvpn.DiscoList.Servers, nil
	}
	file := "server_list.json"
	body, err := getDiscoFile("server_list.json")
	if err != nil {
		return "", &GetListError{File: file, Err: err}
	}
	eduvpn.EnsureDisco()
	eduvpn.DiscoList.Servers = &body
	return body, nil
}