package ldap

import (
	"crypto/rand"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"log"

	"git.nixc.us/a250/ss-atlas/internal/config"
	goldap "github.com/go-ldap/ldap/v3"
)

type Client struct {
	cfg *config.Config
	gql *gqlClient
}

type ProvisionResult struct {
	Username string
	Password string
	IsNew    bool
}

func New(cfg *config.Config) *Client {
	adminUID := "admin"
	return &Client{
		cfg: cfg,
		gql: newGQLClient(cfg.LLDAPHttpURL, adminUID, cfg.LDAPAdminPassword),
	}
}

func (c *Client) connect() (*goldap.Conn, error) {
	conn, err := goldap.DialURL(c.cfg.LDAPUrl)
	if err != nil {
		return nil, fmt.Errorf("ldap dial: %w", err)
	}
	if err := conn.Bind(c.cfg.LDAPAdminDN, c.cfg.LDAPAdminPassword); err != nil {
		conn.Close()
		return nil, fmt.Errorf("ldap bind: %w", err)
	}
	return conn, nil
}

func (c *Client) ProvisionUser(username, email, stripeCustomerID, phone string) (*ProvisionResult, error) {
	conn, err := c.connect()
	if err != nil {
		return nil, err
	}
	defer conn.Close()

	exists, err := c.userExists(conn, username)
	if err != nil {
		return nil, err
	}
	if exists {
		log.Printf("ldap user %s already exists", username)
		if phone != "" {
			_ = c.SetCustomerPhone(username, phone)
		}
		_ = c.ensureDisplayName(conn, username, email)
		return &ProvisionResult{Username: username, IsNew: false}, nil
	}

	password := generatePassword()
	userDN := fmt.Sprintf("uid=%s,ou=people,%s", username, c.cfg.LDAPBaseDN)

	addReq := goldap.NewAddRequest(userDN, nil)
	addReq.Attribute("objectClass", []string{"inetOrgPerson"})
	addReq.Attribute("cn", []string{username})
	addReq.Attribute("sn", []string{username})
	addReq.Attribute("uid", []string{username})
	addReq.Attribute("mail", []string{email})
	addReq.Attribute("displayName", []string{email})
	if phone != "" {
		addReq.Attribute("telephoneNumber", []string{phone})
	}

	if err := conn.Add(addReq); err != nil {
		return nil, fmt.Errorf("ldap add user %s: %w", username, err)
	}

	pwReq := goldap.NewPasswordModifyRequest(userDN, "", password)
	if _, err := conn.PasswordModify(pwReq); err != nil {
		return nil, fmt.Errorf("ldap set password for %s: %w", username, err)
	}

	if stripeCustomerID != "" {
		if err := c.SetStripeCustomerID(username, stripeCustomerID); err != nil {
			log.Printf("warning: failed to set stripe customer id for %s: %v", username, err)
		}
	}
	if phone != "" {
		if err := c.SetCustomerPhone(username, phone); err != nil {
			log.Printf("warning: failed to set customer phone for %s: %v", username, err)
		}
	}

	log.Printf("created ldap user %s (%s)", username, email)
	return &ProvisionResult{Username: username, Password: password, IsNew: true}, nil
}

func (c *Client) ensureDisplayName(conn *goldap.Conn, username, email string) error {
	userDN := fmt.Sprintf("uid=%s,ou=people,%s", username, c.cfg.LDAPBaseDN)
	modReq := goldap.NewModifyRequest(userDN, nil)
	modReq.Replace("displayName", []string{email})
	if err := conn.Modify(modReq); err != nil {
		log.Printf("ldap ensure displayName for %s: %v (may already be set)", username, err)
		return err
	}
	log.Printf("ldap set displayName for %s to %s", username, email)
	return nil
}

func (c *Client) EnsureUser(username, email, stripeCustomerID, phone string) error {
	_, err := c.ProvisionUser(username, email, stripeCustomerID, phone)
	return err
}

func (c *Client) AddToGroup(username, groupName string) error {
	groupID, err := c.getGroupID(groupName)
	if err != nil {
		return fmt.Errorf("resolve group %s: %w", groupName, err)
	}

	query := `mutation($userId: String!, $groupId: Int!) { addUserToGroup(userId: $userId, groupId: $groupId) { ok } }`
	_, err = c.gql.exec(query, map[string]any{"userId": username, "groupId": groupID})
	if err != nil {
		return fmt.Errorf("add %s to group %s: %w", username, groupName, err)
	}
	log.Printf("added %s to group %s", username, groupName)
	return nil
}

func (c *Client) RemoveFromGroup(username, groupName string) error {
	groupID, err := c.getGroupID(groupName)
	if err != nil {
		return fmt.Errorf("resolve group %s: %w", groupName, err)
	}

	query := `mutation($userId: String!, $groupId: Int!) { removeUserFromGroup(userId: $userId, groupId: $groupId) { ok } }`
	_, err = c.gql.exec(query, map[string]any{"userId": username, "groupId": groupID})
	if err != nil {
		return fmt.Errorf("remove %s from group %s: %w", username, groupName, err)
	}
	log.Printf("removed %s from group %s", username, groupName)
	return nil
}

func (c *Client) IsInGroup(username, groupName string) (bool, error) {
	query := `query($userId: String!) { user(userId: $userId) { groups { displayName } } }`
	data, err := c.gql.exec(query, map[string]any{"userId": username})
	if err != nil {
		return false, err
	}

	var result struct {
		User struct {
			Groups []struct {
				DisplayName string `json:"displayName"`
			} `json:"groups"`
		} `json:"user"`
	}
	if err := json.Unmarshal(data, &result); err != nil {
		return false, err
	}

	for _, g := range result.User.Groups {
		if g.DisplayName == groupName {
			return true, nil
		}
	}
	return false, nil
}

func (c *Client) SetStripeCustomerID(username, customerID string) error {
	query := `mutation($userId: String!, $attrs: [AttributeValueInput!]!) {
		updateUser(user: { id: $userId, insertAttributes: $attrs }) { ok }
	}`
	attrs := []map[string]any{
		{"name": "stripe-customer-id", "value": []string{customerID}},
	}
	_, err := c.gql.exec(query, map[string]any{"userId": username, "attrs": attrs})
	return err
}

func (c *Client) SetCustomerPhone(username, phone string) error {
	if phone == "" {
		return nil
	}
	query := `mutation($userId: String!, $attrs: [AttributeValueInput!]!) {
		updateUser(user: { id: $userId, insertAttributes: $attrs }) { ok }
	}`
	attrs := []map[string]any{
		{"name": "customer-phone", "value": []string{phone}},
	}
	_, err := c.gql.exec(query, map[string]any{"userId": username, "attrs": attrs})
	return err
}

func (c *Client) SetCustomerDomain(username, domain string) error {
	if domain == "" {
		return nil
	}
	query := `mutation($userId: String!, $attrs: [AttributeValueInput!]!) {
		updateUser(user: { id: $userId, insertAttributes: $attrs }) { ok }
	}`
	attrs := []map[string]any{
		{"name": "customer-domain", "value": []string{domain}},
	}
	_, err := c.gql.exec(query, map[string]any{"userId": username, "attrs": attrs})
	return err
}

func (c *Client) GetCustomerDomain(username string) (string, error) {
	query := `query($userId: String!) { user(userId: $userId) { attributes { name value } } }`
	data, err := c.gql.exec(query, map[string]any{"userId": username})
	if err != nil {
		return "", err
	}
	var result struct {
		User struct {
			Attributes []struct {
				Name  string   `json:"name"`
				Value []string `json:"value"`
			} `json:"attributes"`
		} `json:"user"`
	}
	if err := json.Unmarshal(data, &result); err != nil {
		return "", err
	}
	for _, attr := range result.User.Attributes {
		if attr.Name == "customer-domain" && len(attr.Value) > 0 {
			return attr.Value[0], nil
		}
	}
	return "", nil
}

func (c *Client) GetStripeCustomerID(username string) (string, error) {
	query := `query($userId: String!) { user(userId: $userId) { attributes { name value } } }`
	data, err := c.gql.exec(query, map[string]any{"userId": username})
	if err != nil {
		return "", err
	}

	var result struct {
		User struct {
			Attributes []struct {
				Name  string   `json:"name"`
				Value []string `json:"value"`
			} `json:"attributes"`
		} `json:"user"`
	}
	if err := json.Unmarshal(data, &result); err != nil {
		return "", err
	}

	for _, attr := range result.User.Attributes {
		if attr.Name == "stripe-customer-id" && len(attr.Value) > 0 {
			return attr.Value[0], nil
		}
	}
	return "", nil
}

func (c *Client) FindUserByStripeID(stripeCustomerID string) (string, error) {
	query := `query { users(filters: {}) { id attributes { name value } } }`
	data, err := c.gql.exec(query, nil)
	if err != nil {
		return "", err
	}

	var result struct {
		Users []struct {
			ID         string `json:"id"`
			Attributes []struct {
				Name  string   `json:"name"`
				Value []string `json:"value"`
			} `json:"attributes"`
		} `json:"users"`
	}
	if err := json.Unmarshal(data, &result); err != nil {
		return "", err
	}

	for _, u := range result.Users {
		for _, attr := range u.Attributes {
			if attr.Name == "stripe-customer-id" && len(attr.Value) > 0 && attr.Value[0] == stripeCustomerID {
				return u.ID, nil
			}
		}
	}
	return "", fmt.Errorf("no user found with stripe customer %s", stripeCustomerID)
}

// CountCustomers returns the number of users who have completed checkout (have stripe-customer-id).
// Used to enforce signup limits.
func (c *Client) CountCustomers() (int, error) {
	query := `query { users(filters: {}) { id attributes { name value } } }`
	data, err := c.gql.exec(query, nil)
	if err != nil {
		return 0, err
	}

	var result struct {
		Users []struct {
			Attributes []struct {
				Name  string   `json:"name"`
				Value []string `json:"value"`
			} `json:"attributes"`
		} `json:"users"`
	}
	if err := json.Unmarshal(data, &result); err != nil {
		return 0, err
	}

	n := 0
	for _, u := range result.Users {
		for _, attr := range u.Attributes {
			if attr.Name == "stripe-customer-id" && len(attr.Value) > 0 && attr.Value[0] != "" {
				n++
				break
			}
		}
	}
	return n, nil
}

func (c *Client) getGroupID(groupName string) (int, error) {
	query := `query { groups { id displayName } }`
	data, err := c.gql.exec(query, nil)
	if err != nil {
		return 0, err
	}

	var result struct {
		Groups []struct {
			ID          int    `json:"id"`
			DisplayName string `json:"displayName"`
		} `json:"groups"`
	}
	if err := json.Unmarshal(data, &result); err != nil {
		return 0, err
	}

	for _, g := range result.Groups {
		if g.DisplayName == groupName {
			return g.ID, nil
		}
	}
	return 0, fmt.Errorf("group %s not found", groupName)
}

func (c *Client) userExists(conn *goldap.Conn, username string) (bool, error) {
	searchReq := goldap.NewSearchRequest(
		fmt.Sprintf("ou=people,%s", c.cfg.LDAPBaseDN),
		goldap.ScopeWholeSubtree, goldap.NeverDerefAliases, 1, 0, false,
		fmt.Sprintf("(uid=%s)", goldap.EscapeFilter(username)),
		[]string{"uid"},
		nil,
	)

	result, err := conn.Search(searchReq)
	if err != nil {
		return false, fmt.Errorf("ldap search: %w", err)
	}

	return len(result.Entries) > 0, nil
}

func generatePassword() string {
	b := make([]byte, 18)
	if _, err := rand.Read(b); err != nil {
		panic("crypto/rand failed: " + err.Error())
	}
	return base64.URLEncoding.EncodeToString(b)
}