package cluster

import (
	"context"
	"crypto/tls"
	"encoding/base64"
	"encoding/json"
	"fmt"
	"html"
	"io"
	"net/http"
	"net/http/cookiejar"
	neturl "net/url"
	"regexp"
	"strings"
	"time"

	"scm.bstein.dev/bstein/ananke/internal/config"
)

type keycloakTokenResponse struct {
	AccessToken string `json:"access_token"`
}

type keycloakUser struct {
	ID string `json:"id"`
}

type keycloakImpersonationResponse struct {
	Redirect string `json:"redirect"`
}

type kubernetesSecret struct {
	Data map[string]string `json:"data"`
}

var keycloakLoginFormActionPattern = regexp.MustCompile(`(?is)<form[^>]*id=["']kc-form-login["'][^>]*action=["']([^"']+)["']`)

// checklistAuthHTTPClient runs one orchestration or CLI step.
// Signature: (o *Orchestrator) checklistAuthHTTPClient(ctx context.Context, timeout time.Duration, insecureSkipTLS bool) (*http.Client, error).
// Why: startup checklist checks that require real user behavior need an
// authenticated robotuser browser-like session before probing service pages.
func (o *Orchestrator) checklistAuthHTTPClient(ctx context.Context, timeout time.Duration, insecureSkipTLS bool) (*http.Client, error) {
	jar, _ := cookiejar.New(nil)
	transport := &http.Transport{}
	if insecureSkipTLS {
		transport.TLSClientConfig = &tls.Config{InsecureSkipVerify: true}
	}
	client := &http.Client{
		Timeout:   timeout,
		Transport: transport,
		Jar:       jar,
	}
	if err := o.authenticateRobotChecklistSession(ctx, client); err != nil {
		return nil, err
	}
	return client, nil
}

// authenticateRobotChecklistSession runs one orchestration or CLI step.
// Signature: (o *Orchestrator) authenticateRobotChecklistSession(ctx context.Context, client *http.Client) error.
// Why: authenticated checklist probes must reflect what a human sees after
// Keycloak login, not only pre-auth redirects.
func (o *Orchestrator) authenticateRobotChecklistSession(ctx context.Context, client *http.Client) error {
	auth := o.cfg.Startup.ServiceChecklistAuth
	mode := strings.TrimSpace(auth.Mode)
	if mode == "" || mode == "none" {
		return fmt.Errorf("startup checklist auth mode is disabled")
	}
	if mode != "keycloak_robotuser" {
		return fmt.Errorf("unsupported startup checklist auth mode %q", mode)
	}

	adminUser, adminPassword, err := o.keycloakAdminCredentials(ctx, auth)
	if err != nil {
		return err
	}
	if err := o.keycloakAdminBrowserLogin(ctx, client, auth, adminUser, adminPassword); err != nil {
		return fmt.Errorf("initialize keycloak admin browser session: %w", err)
	}
	adminToken, err := o.keycloakAdminToken(ctx, client, auth, adminUser, adminPassword)
	if err != nil {
		return err
	}
	robotUserID, err := o.keycloakRobotUserID(ctx, client, auth, adminToken)
	if err != nil {
		return err
	}
	redirectURL, err := o.keycloakImpersonationRedirect(ctx, client, auth, adminToken, robotUserID)
	if err != nil {
		return err
	}
	if strings.TrimSpace(redirectURL) == "" {
		redirectURL = keycloakBaseURL(auth) + "/realms/" + strings.TrimSpace(auth.Realm) + "/account/"
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, redirectURL, nil)
	if err != nil {
		return fmt.Errorf("build robot redirect request: %w", err)
	}
	req.Header.Set("User-Agent", "ananke/startup-checklist")
	resp, err := client.Do(req)
	if err != nil {
		return fmt.Errorf("initialize robot session redirect: %w", err)
	}
	defer resp.Body.Close()
	_, _ = io.Copy(io.Discard, io.LimitReader(resp.Body, 1024))
	finalURL := ""
	if resp.Request != nil && resp.Request.URL != nil {
		finalURL = strings.TrimSpace(resp.Request.URL.String())
	}
	if strings.Contains(finalURL, "/protocol/openid-connect/auth") || strings.Contains(finalURL, "/login-actions/authenticate") {
		return fmt.Errorf("robot session bootstrap ended on keycloak login flow: %s", finalURL)
	}
	return nil
}

// keycloakAdminBrowserLogin runs one orchestration or CLI step.
// Signature: (o *Orchestrator) keycloakAdminBrowserLogin(ctx context.Context, client *http.Client, auth config.ServiceChecklistAuthSettings, adminUser string, adminPassword string) error.
// Why: Keycloak impersonation only yields a usable robot session cookie when the
// client already has a real admin browser session; token-only API calls are not
// sufficient for downstream OIDC-gated service checks.
func (o *Orchestrator) keycloakAdminBrowserLogin(ctx context.Context, client *http.Client, auth config.ServiceChecklistAuthSettings, adminUser string, adminPassword string) error {
	baseURL := keycloakBaseURL(auth)
	authURL := baseURL + "/realms/master/protocol/openid-connect/auth?" + keycloakAdminConsoleAuthQuery(baseURL).Encode()
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, authURL, nil)
	if err != nil {
		return fmt.Errorf("build keycloak admin auth request: %w", err)
	}
	req.Header.Set("User-Agent", "ananke/startup-checklist")
	resp, err := client.Do(req)
	if err != nil {
		return fmt.Errorf("request keycloak admin auth page: %w", err)
	}
	defer resp.Body.Close()
	body, _ := io.ReadAll(io.LimitReader(resp.Body, 512*1024))
	if resp.StatusCode/100 != 2 {
		return fmt.Errorf("keycloak admin auth page request failed status=%d body=%q", resp.StatusCode, compactHTTPBody(body))
	}
	actionURL, err := keycloakLoginFormAction(string(body), baseURL)
	if err != nil {
		return err
	}

	form := neturl.Values{}
	form.Set("username", adminUser)
	form.Set("password", adminPassword)
	form.Set("credentialId", "")

	loginReq, err := http.NewRequestWithContext(ctx, http.MethodPost, actionURL, strings.NewReader(form.Encode()))
	if err != nil {
		return fmt.Errorf("build keycloak admin login request: %w", err)
	}
	loginReq.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	loginReq.Header.Set("User-Agent", "ananke/startup-checklist")

	loginResp, err := client.Do(loginReq)
	if err != nil {
		return fmt.Errorf("request keycloak admin login submit: %w", err)
	}
	defer loginResp.Body.Close()
	loginBody, _ := io.ReadAll(io.LimitReader(loginResp.Body, 512*1024))
	finalURL := ""
	if loginResp.Request != nil && loginResp.Request.URL != nil {
		finalURL = strings.TrimSpace(loginResp.Request.URL.String())
	}
	if loginResp.StatusCode >= 500 {
		return fmt.Errorf("keycloak admin login failed status=%d body=%q", loginResp.StatusCode, compactHTTPBody(loginBody))
	}
	if strings.Contains(finalURL, "/login-actions/authenticate") || strings.Contains(finalURL, "/protocol/openid-connect/auth") {
		return fmt.Errorf("keycloak admin login did not complete (final_url=%q)", finalURL)
	}
	if strings.Contains(strings.ToLower(string(loginBody)), "kc-form-login") {
		return fmt.Errorf("keycloak admin login form still present after submit")
	}
	return nil
}

// keycloakAdminCredentials runs one orchestration or CLI step.
// Signature: (o *Orchestrator) keycloakAdminCredentials(ctx context.Context, auth config.ServiceChecklistAuthSettings) (string, string, error).
// Why: robotuser impersonation uses a cluster-managed admin secret so startup
// checks do not rely on interactive credentials.
func (o *Orchestrator) keycloakAdminCredentials(ctx context.Context, auth config.ServiceChecklistAuthSettings) (string, string, error) {
	namespace := strings.TrimSpace(auth.AdminSecretNamespace)
	name := strings.TrimSpace(auth.AdminSecretName)
	userKey := strings.TrimSpace(auth.AdminSecretUsernameKey)
	passwordKey := strings.TrimSpace(auth.AdminSecretPasswordKey)

	username, err := o.kubernetesSecretValue(ctx, namespace, name, userKey)
	if err != nil {
		return "", "", fmt.Errorf("read keycloak admin username from secret %s/%s: %w", namespace, name, err)
	}
	password, err := o.kubernetesSecretValue(ctx, namespace, name, passwordKey)
	if err != nil {
		return "", "", fmt.Errorf("read keycloak admin password from secret %s/%s: %w", namespace, name, err)
	}
	return username, password, nil
}

// kubernetesSecretValue runs one orchestration or CLI step.
// Signature: (o *Orchestrator) kubernetesSecretValue(ctx context.Context, namespace string, name string, key string) (string, error).
// Why: checklist auth depends on secret-backed credentials and should decode
// them directly from Kubernetes rather than shelling out to external tools.
func (o *Orchestrator) kubernetesSecretValue(ctx context.Context, namespace string, name string, key string) (string, error) {
	out, err := o.kubectl(ctx, 25*time.Second, "-n", namespace, "get", "secret", name, "-o", "json")
	if err != nil {
		return "", fmt.Errorf("kubectl get secret: %w", err)
	}
	var doc kubernetesSecret
	if err := json.Unmarshal([]byte(out), &doc); err != nil {
		return "", fmt.Errorf("decode secret json: %w", err)
	}
	encoded, ok := doc.Data[key]
	if !ok {
		return "", fmt.Errorf("key %q not present in secret", key)
	}
	decoded, err := base64.StdEncoding.DecodeString(strings.TrimSpace(encoded))
	if err != nil {
		return "", fmt.Errorf("decode base64 secret value: %w", err)
	}
	value := strings.TrimSpace(string(decoded))
	if value == "" {
		return "", fmt.Errorf("decoded value is empty")
	}
	return value, nil
}

// keycloakAdminToken runs one orchestration or CLI step.
// Signature: (o *Orchestrator) keycloakAdminToken(ctx context.Context, client *http.Client, auth config.ServiceChecklistAuthSettings, adminUser string, adminPassword string) (string, error).
// Why: admin API access is needed to impersonate robotuser for deterministic
// user-journey checks across OIDC-gated services.
func (o *Orchestrator) keycloakAdminToken(ctx context.Context, client *http.Client, auth config.ServiceChecklistAuthSettings, adminUser string, adminPassword string) (string, error) {
	form := neturl.Values{}
	form.Set("grant_type", "password")
	form.Set("client_id", "admin-cli")
	form.Set("username", adminUser)
	form.Set("password", adminPassword)

	tokenURL := keycloakBaseURL(auth) + "/realms/master/protocol/openid-connect/token"
	req, err := http.NewRequestWithContext(ctx, http.MethodPost, tokenURL, strings.NewReader(form.Encode()))
	if err != nil {
		return "", fmt.Errorf("build admin token request: %w", err)
	}
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	req.Header.Set("User-Agent", "ananke/startup-checklist")

	resp, err := client.Do(req)
	if err != nil {
		return "", fmt.Errorf("request admin token: %w", err)
	}
	defer resp.Body.Close()
	body, _ := io.ReadAll(io.LimitReader(resp.Body, 64*1024))
	if resp.StatusCode/100 != 2 {
		return "", fmt.Errorf("admin token request failed status=%d body=%q", resp.StatusCode, compactHTTPBody(body))
	}

	var payload keycloakTokenResponse
	if err := json.Unmarshal(body, &payload); err != nil {
		return "", fmt.Errorf("decode admin token response: %w", err)
	}
	token := strings.TrimSpace(payload.AccessToken)
	if token == "" {
		return "", fmt.Errorf("admin token response missing access_token")
	}
	return token, nil
}

// keycloakRobotUserID runs one orchestration or CLI step.
// Signature: (o *Orchestrator) keycloakRobotUserID(ctx context.Context, client *http.Client, auth config.ServiceChecklistAuthSettings, adminToken string) (string, error).
// Why: impersonation requires the concrete user id and should fail fast when
// robotuser is missing from the realm.
func (o *Orchestrator) keycloakRobotUserID(ctx context.Context, client *http.Client, auth config.ServiceChecklistAuthSettings, adminToken string) (string, error) {
	base := keycloakBaseURL(auth)
	realm := strings.TrimSpace(auth.Realm)
	username := strings.TrimSpace(auth.RobotUsername)
	query := neturl.Values{}
	query.Set("username", username)
	query.Set("exact", "true")
	usersURL := base + "/admin/realms/" + realm + "/users?" + query.Encode()

	req, err := http.NewRequestWithContext(ctx, http.MethodGet, usersURL, nil)
	if err != nil {
		return "", fmt.Errorf("build robot user lookup request: %w", err)
	}
	req.Header.Set("Authorization", "Bearer "+adminToken)
	req.Header.Set("User-Agent", "ananke/startup-checklist")

	resp, err := client.Do(req)
	if err != nil {
		return "", fmt.Errorf("lookup robot user: %w", err)
	}
	defer resp.Body.Close()
	body, _ := io.ReadAll(io.LimitReader(resp.Body, 64*1024))
	if resp.StatusCode/100 != 2 {
		return "", fmt.Errorf("robot user lookup failed status=%d body=%q", resp.StatusCode, compactHTTPBody(body))
	}

	var users []keycloakUser
	if err := json.Unmarshal(body, &users); err != nil {
		return "", fmt.Errorf("decode robot user lookup response: %w", err)
	}
	if len(users) == 0 || strings.TrimSpace(users[0].ID) == "" {
		return "", fmt.Errorf("robot user %q not found in realm %q", username, realm)
	}
	return strings.TrimSpace(users[0].ID), nil
}

// keycloakImpersonationRedirect runs one orchestration or CLI step.
// Signature: (o *Orchestrator) keycloakImpersonationRedirect(ctx context.Context, client *http.Client, auth config.ServiceChecklistAuthSettings, adminToken string, robotUserID string) (string, error).
// Why: opening a real impersonated browser session guarantees checks evaluate
// post-login app behavior instead of only auth-gateway redirects.
func (o *Orchestrator) keycloakImpersonationRedirect(ctx context.Context, client *http.Client, auth config.ServiceChecklistAuthSettings, adminToken string, robotUserID string) (string, error) {
	base := keycloakBaseURL(auth)
	realm := strings.TrimSpace(auth.Realm)
	impersonateURL := base + "/admin/realms/" + realm + "/users/" + strings.TrimSpace(robotUserID) + "/impersonation"

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, impersonateURL, http.NoBody)
	if err != nil {
		return "", fmt.Errorf("build robot impersonation request: %w", err)
	}
	req.Header.Set("Authorization", "Bearer "+adminToken)
	req.Header.Set("User-Agent", "ananke/startup-checklist")

	resp, err := client.Do(req)
	if err != nil {
		return "", fmt.Errorf("request robot impersonation: %w", err)
	}
	defer resp.Body.Close()
	body, _ := io.ReadAll(io.LimitReader(resp.Body, 64*1024))
	if resp.StatusCode/100 != 2 {
		return "", fmt.Errorf("robot impersonation failed status=%d body=%q", resp.StatusCode, compactHTTPBody(body))
	}

	var payload keycloakImpersonationResponse
	if err := json.Unmarshal(body, &payload); err != nil {
		return "", fmt.Errorf("decode robot impersonation response: %w", err)
	}
	return strings.TrimSpace(payload.Redirect), nil
}

// keycloakBaseURL runs one orchestration or CLI step.
// Signature: keycloakBaseURL(auth config.ServiceChecklistAuthSettings) string.
// Why: centralizing URL normalization keeps auth request construction stable.
func keycloakBaseURL(auth config.ServiceChecklistAuthSettings) string {
	return strings.TrimRight(strings.TrimSpace(auth.KeycloakBaseURL), "/")
}

// keycloakAdminConsoleAuthQuery runs one orchestration or CLI step.
// Signature: keycloakAdminConsoleAuthQuery() neturl.Values.
// Why: centralizes required Keycloak admin-console auth parameters, including
// PKCE fields required by current Keycloak defaults.
func keycloakAdminConsoleAuthQuery(baseURL string) neturl.Values {
	query := neturl.Values{}
	query.Set("client_id", "security-admin-console")
	query.Set("redirect_uri", strings.TrimRight(strings.TrimSpace(baseURL), "/")+"/admin/master/console/")
	query.Set("response_type", "code")
	query.Set("scope", "openid")
	query.Set("state", "ananke-startup-checklist")
	query.Set("nonce", "ananke-startup-checklist")
	query.Set("code_challenge_method", "S256")
	query.Set("code_challenge", "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
	return query
}

// keycloakLoginFormAction runs one orchestration or CLI step.
// Signature: keycloakLoginFormAction(page string, baseURL string) (string, error).
// Why: Keycloak's login form action carries session-bound query params and must
// be parsed from the rendered page before posting credentials.
func keycloakLoginFormAction(page string, baseURL string) (string, error) {
	matches := keycloakLoginFormActionPattern.FindStringSubmatch(page)
	if len(matches) < 2 || strings.TrimSpace(matches[1]) == "" {
		return "", fmt.Errorf("keycloak login page missing kc-form-login action")
	}
	action := html.UnescapeString(strings.TrimSpace(matches[1]))
	if strings.HasPrefix(action, "/") {
		return strings.TrimRight(strings.TrimSpace(baseURL), "/") + action, nil
	}
	if strings.HasPrefix(action, "http://") || strings.HasPrefix(action, "https://") {
		return action, nil
	}
	return "", fmt.Errorf("keycloak login action uses unsupported format %q", action)
}

// compactHTTPBody runs one orchestration or CLI step.
// Signature: compactHTTPBody(raw []byte) string.
// Why: checklist auth errors should include a readable body summary without
// leaking multi-line payload noise into orchestrator logs.
func compactHTTPBody(raw []byte) string {
	text := strings.TrimSpace(string(raw))
	if text == "" {
		return ""
	}
	return strings.Join(strings.Fields(text), " ")
}