package main

import (
	"encoding/json"
	"fmt"
	"path/filepath"
	"regexp"
	"sort"
	"strconv"
	"strings"
	"time"
)

const (
	service       = "org.freedesktop.secrets"
	servicePath   = "/org/freedesktop/secrets"
	collectionDir = "/org/freedesktop/secrets/collection/"
	busTimeout    = 10 * time.Second
)

// busctl runs one busctl call on the account's session bus and answers its JSON.
func busctl(s Session, args ...string) (json.RawMessage, error) {
	r, err := s.run(busTimeout, "", "busctl", append([]string{"--user", "--json=short"}, args...)...)
	if err != nil {
		return nil, err
	}
	if r.Code != 0 {
		return nil, fmt.Errorf("the secret service: %s", strings.TrimSpace(r.Stderr))
	}
	var v struct {
		Data json.RawMessage `json:"data"`
	}
	if err := json.Unmarshal([]byte(r.Stdout), &v); err != nil {
		return nil, fmt.Errorf("busctl answered no JSON: %w", err)
	}
	return v.Data, nil
}

// collectionID is the part of a collection's object path after .../collection/, unescaped the way
// the Secret Service escapes it ("_5f" is "_").
func collectionID(path string) string { return strings.TrimPrefix(path, collectionDir) }

func collectionPath(id string) string { return collectionDir + id }

var validID = regexp.MustCompile(`^[A-Za-z0-9_]+$`)

// Collection is one keyring.
type Collection struct {
	ID       string `json:"id"`
	Label    string `json:"label"`
	Locked   bool   `json:"locked"`
	Items    int    `json:"items"`
	Created  string `json:"created,omitempty"`
	Modified string `json:"modified,omitempty"`
	Default  bool   `json:"default,omitempty"`
}

// CollectionsResult is what gnome_keyring_collections answers.
type CollectionsResult struct {
	Collections []Collection `json:"collections"`
}

func paths(s Session) ([]string, error) {
	raw, err := busctl(s, "get-property", service, servicePath, "org.freedesktop.Secret.Service", "Collections")
	if err != nil {
		return nil, err
	}
	var out []string
	if err := json.Unmarshal(raw, &out); err != nil {
		return nil, fmt.Errorf("the collections: %w", err)
	}
	return out, nil
}

func defaultCollection(s Session) string {
	raw, err := busctl(s, "call", service, servicePath, "org.freedesktop.Secret.Service", "ReadAlias", "s", "default")
	if err != nil {
		return ""
	}
	var out []string
	if json.Unmarshal(raw, &out) != nil || len(out) == 0 || out[0] == "/" {
		return ""
	}
	return collectionID(out[0])
}

// describe reads a collection's properties: label, lock, the number of items (never the items), times.
func describe(s Session, path string) (Collection, error) {
	raw, err := busctl(s, "call", service, path, "org.freedesktop.DBus.Properties", "GetAll", "s", "org.freedesktop.Secret.Collection")
	if err != nil {
		return Collection{}, err
	}
	return parseCollection(path, raw)
}

func parseCollection(path string, raw json.RawMessage) (Collection, error) {
	var answer []map[string]struct {
		Data json.RawMessage `json:"data"`
	}
	if err := json.Unmarshal(raw, &answer); err != nil || len(answer) != 1 {
		return Collection{}, fmt.Errorf("collection %s: not a property map", path)
	}
	p := answer[0]
	c := Collection{ID: collectionID(path)}
	_ = json.Unmarshal(p["Label"].Data, &c.Label)
	_ = json.Unmarshal(p["Locked"].Data, &c.Locked)
	var items []string
	_ = json.Unmarshal(p["Items"].Data, &items)
	c.Items = len(items)
	for key, into := range map[string]*string{"Created": &c.Created, "Modified": &c.Modified} {
		var t int64
		if json.Unmarshal(p[key].Data, &t) == nil && t > 0 {
			*into = time.Unix(t, 0).Format(time.RFC3339)
		}
	}
	return c, nil
}

// Collections are the operator's keyrings.
func Collections() (CollectionsResult, error) {
	s, err := findBus()
	if err != nil {
		return CollectionsResult{}, err
	}
	ps, err := paths(s)
	if err != nil {
		return CollectionsResult{}, err
	}
	def := defaultCollection(s)
	out := CollectionsResult{Collections: []Collection{}}
	for _, p := range ps {
		c, err := describe(s, p)
		if err != nil {
			return CollectionsResult{}, err
		}
		c.Default = c.ID == def
		out.Collections = append(out.Collections, c)
	}
	sort.Slice(out.Collections, func(i, j int) bool { return out.Collections[i].ID < out.Collections[j].ID })
	return out, nil
}

// UnlockedResult is what gnome_keyring_unlocked answers.
type UnlockedResult struct {
	Daemon  bool        `json:"daemon_running"`
	Login   *Collection `json:"login,omitempty"`
	Default *Collection `json:"default,omitempty"`
	Note    string      `json:"note,omitempty"`
}

// Unlocked is whether the login and default keyrings are unlocked.
func Unlocked() (UnlockedResult, error) {
	s, err := findBus()
	if err != nil {
		return UnlockedResult{}, err
	}
	// gnome-keyring-daemon, as the kernel shortens a command's name to 15 characters.
	out := UnlockedResult{Daemon: len(processesOf("gnome-keyring-d")) > 0}
	if c, err := describe(s, collectionPath("login")); err == nil {
		out.Login = &c
	} else {
		out.Note = "no login keyring: " + err.Error()
	}
	if def := defaultCollection(s); def != "" && def != "login" {
		if c, err := describe(s, collectionPath(def)); err == nil {
			c.Default = true
			out.Default = &c
		}
	} else if out.Login != nil {
		out.Login.Default = def == "login"
	}
	return out, nil
}

// LockResult is what gnome_keyring_lock answers.
type LockResult struct {
	Collection string `json:"collection"`
	Locked     bool   `json:"locked"`
}

// Lock locks one keyring.
func Lock(id string) (LockResult, error) {
	if id == "" {
		id = "login"
	}
	if !validID.MatchString(id) {
		return LockResult{}, fmt.Errorf("collection %q is not a keyring id", id)
	}
	s, err := findBus()
	if err != nil {
		return LockResult{}, err
	}
	if _, err := busctl(s, "call", service, servicePath, "org.freedesktop.Secret.Service", "Lock", "ao", "1", collectionPath(id)); err != nil {
		return LockResult{}, err
	}
	c, err := describe(s, collectionPath(id))
	if err != nil {
		return LockResult{}, err
	}
	return LockResult{Collection: id, Locked: c.Locked}, nil
}

// Key is one key the ssh agent holds.
type Key struct {
	Bits        int    `json:"bits"`
	Fingerprint string `json:"fingerprint"`
	Comment     string `json:"comment"`
	Type        string `json:"type"`
}

// SSHKeysResult is what gnome_keyring_ssh_keys answers.
type SSHKeysResult struct {
	Agent string `json:"agent"`
	Keys  []Key  `json:"keys"`
	Note  string `json:"note,omitempty"`
}

// agentSocket is gcr's ssh agent socket, which its user socket unit listens on.
func agentSocket(s Session) string { return filepath.Join(s.RuntimeDir, "gcr", "ssh") }

var keyLine = regexp.MustCompile(`^(\d+)\s+(\S+)\s+(.*?)\s*\(([A-Z0-9-]+)\)$`)

func parseKeys(out string) []Key {
	keys := []Key{}
	for _, line := range strings.Split(out, "\n") {
		m := keyLine.FindStringSubmatch(strings.TrimSpace(line))
		if m == nil {
			continue
		}
		bits, _ := strconv.Atoi(m[1])
		keys = append(keys, Key{Bits: bits, Fingerprint: m[2], Comment: m[3], Type: m[4]})
	}
	return keys
}

// SSHKeys lists what gcr's ssh agent holds, by fingerprint.
func SSHKeys() (SSHKeysResult, error) {
	s, err := findBus()
	if err != nil {
		return SSHKeysResult{}, err
	}
	sock := agentSocket(s)
	// The agent is named for this one command only; nothing else of the tool's environment changes.
	r, err := s.run(busTimeout, "", "env", "SSH_AUTH_SOCK="+sock, "ssh-add", "-l", "-E", "sha256")
	if err != nil {
		return SSHKeysResult{}, err
	}
	out := SSHKeysResult{Agent: sock, Keys: parseKeys(r.Stdout)}
	switch r.Code {
	case 0:
	case 1:
		out.Note = "the agent holds no keys"
	case 127:
		return SSHKeysResult{}, fmt.Errorf("ssh-add is not installed on this machine")
	default:
		return SSHKeysResult{}, fmt.Errorf("the ssh agent at %s does not answer: %s (is gcr-ssh-agent.socket enabled?)",
			sock, strings.TrimSpace(r.Stderr))
	}
	return out, nil
}