package main

import (
	"encoding/xml"
	"fmt"
	"io/ioutil"
	"log"
	"net/http"
	"os"
	"os/exec"
	"path"
	"strings"

	"github.com/BurntSushi/toml"
	"github.com/emersion/go-vcard"
	"github.com/google/shlex"
	"github.com/kyoh86/xdg"
)

func main() {
	if err := run(); err != nil {
		log.Fatal(err)
	}
}

func run() error {
	cfg, err := loadConfig()
	if err != nil {
		return err
	}
	book := &AddressBook{
		Endpoint: cfg.Endpoint,
		Username: cfg.Username,
	}
	pw, err := cfg.getPassword()
	if err != nil {
		return fmt.Errorf("could not get password: %w", err)
	}
	book.Password = pw
	var c CardDAVClient

	if len(os.Args) < 2 {
		return fmt.Errorf("insufficient command line arguments")
	}

	resp, err := c.Report(book, os.Args[1])
	if err != nil {
		return fmt.Errorf("could not fetch completions: %w", err)
	}

	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return fmt.Errorf("could not read response: %w", err)
	}
	defer resp.Body.Close()

	var ms Multistatus
	if err := xml.Unmarshal(body, &ms); err != nil {
		return fmt.Errorf("could not unmarshal XML: %w", err)
	}
	for _, resp := range ms.Responses {
		decoder := vcard.NewDecoder(strings.NewReader(resp.Propstat.Prop.AddressData))
		card, err := decoder.Decode()
		if err != nil {
			return fmt.Errorf("could not decode vcard: %w", err)
		}
		emails := card.Values(vcard.FieldEmail)
		fn := card.Get(vcard.FieldFormattedName)
		if len(emails) == 0 {
			continue
		}
		if fn == nil {
			fn = &vcard.Field{}
		}
		for _, email := range emails {
			fmt.Printf("%s\t%s\n", email, fn.Value)
		}
	}
	return nil
}

type config struct {
	Endpoint    string `toml:"endpoint"`
	Username    string `toml:"username"`
	Password    string `toml:"password"`
	PasswordCmd string `toml:"password-cmd"`
}

func (c config) getPassword() (string, error) {
	if c.PasswordCmd != "" {
		cmd, err := c.getPasswordCmd()
		if err != nil {
			return "", err
		}
		stdout, err := cmd.StdoutPipe()
		if err != nil {
			return "", fmt.Errorf("could not set up stdout pipe: %w", err)
		}
		if err := cmd.Start(); err != nil {
			return "", fmt.Errorf("could not start password-cmd: %w", err)
		}
		res, err := ioutil.ReadAll(stdout)
		if err != nil {
			return "", fmt.Errorf("could not read stdout: %w", err)
		}
		if err := cmd.Wait(); err != nil {
			return "", fmt.Errorf("could not run password-cmd: %w", err)
		}
		return strings.TrimSpace(string(res)), nil
	}
	return c.Password, nil
}

func (c config) getPasswordCmd() (*exec.Cmd, error) {
	parts, err := shlex.Split(c.PasswordCmd)
	if err != nil {
		return nil, fmt.Errorf("could not lex password-cmd: %w", err)
	}
	if len(parts) < 1 {
		return nil, fmt.Errorf("empty command")
	}
	if len(parts) > 1 {
		return exec.Command(parts[0], parts[1:]...), nil
	}
	return exec.Command(parts[0]), nil
}

func loadConfig() (*config, error) {
	filename := path.Join(xdg.ConfigHome(), "cdc", "config")
	var cfg config
	if _, err := toml.DecodeFile(filename, &cfg); err != nil {
		return nil, fmt.Errorf("could not read config: %w", err)
	}
	return &cfg, nil
}

type AddressBook struct {
	Endpoint string
	Username string
	Password string
}

type CardDAVClient struct {
	hc http.Client
}

func (c *CardDAVClient) Report(book *AddressBook, search string) (*http.Response, error) {
	req, err := http.NewRequest("REPORT", book.Endpoint, strings.NewReader(`<?xml version="1.0" encoding="utf-8"?>
<C:addressbook-query xmlns:D="DAV:" xmlns:C="urn:ietf:params:xml:ns:carddav">
<D:prop>
  <D:getetag />
  <C:address-data>
    <C:prop name="FN" />
    <C:prop name="EMAIL" />
  </C:address-data>
</D:prop>
<C:filter test="anyof">
  <C:prop-filter name="EMAIL">
    <C:text-match collation="i;unicode-casemap" match-type="contains">`+search+`</C:text-match>
  </C:prop-filter>
  <C:prop-filter name="FN">
    <C:text-match collation="i;unicode-casemap" match-type="contains">`+search+`</C:text-match>
  </C:prop-filter>
</C:filter>
</C:addressbook-query>`))
	if err != nil {
		return nil, err
	}
	req.Header.Add("Depth", "1")
	req.Header.Add("Content-Type", "text/xml; charset=\"utf-8\"")
	if book.Username != "" || book.Password != "" {
		req.SetBasicAuth(book.Username, book.Password)
	}
	return c.hc.Do(req)
}

type Multistatus struct {
	Responses []Response `xml:"response"`
}

type Response struct {
	HREF     string   `xml:"href"`
	Propstat Propstat `xml:"propstat"`
}

type Propstat struct {
	Prop Prop `xml:"prop"`
}

type Prop struct {
	GetETag     string `xml:"getetag"`
	AddressData string `xml:"address-data"`
}