package main

import (
	"encoding/json"
	"fmt"
	"strings"
)

// SessionResponse from /auth/skill-credit/session
type SessionResponse struct {
	AccessToken       string `json:"accessToken"`
	OwnerSessionToken string `json:"ownerSessionToken,omitempty"`
	HookURL           string `json:"hookUrl,omitempty"`
	HookToken         string `json:"hookToken,omitempty"`
	ExpiresIn         int    `json:"expiresIn"`
	ClientID          string `json:"clientId,omitempty"`
	OwnerUserID       string `json:"ownerUserId,omitempty"`
	Balance           int    `json:"balance,omitempty"`
}

// ClientConfigResponse from /auth/skill-credit/client-config
type ClientConfigResponse struct {
	ClientID string                 `json:"clientId"`
	Name     string                 `json:"name"`
	Status   string                 `json:"status"`
	Metadata map[string]interface{} `json:"metadata"`
}

var retryableStatuses = map[int]bool{401: true, 403: true}
var retryableMarkers = []string{
	"session not found or expired",
	"invalid or expired token",
	"unauthorized",
	"client key expired",
	"client key revoked",
}

func isRetryable(resp APIResponse) bool {
	if !retryableStatuses[resp.Status] {
		return false
	}
	body := strings.ToLower(resp.Body)
	if body == "" {
		return true
	}
	for _, m := range retryableMarkers {
		if strings.Contains(body, m) {
			return true
		}
	}
	return false
}

// fetchSession exchanges CLIENT_KEY for a session token.
func fetchSession(cfg Config) (*SessionResponse, error) {
	if cfg.ClientKey == "" {
		return nil, fmt.Errorf("CLIENT_KEY is required")
	}

	payload := fmt.Sprintf(`{"clientKey":"%s"}`, cfg.ClientKey)
	resp, err := doHTTP("POST", cfg.AuthBase+"/auth/skill-credit/session", "", payload, nil)
	if err != nil {
		return nil, fmt.Errorf("session request failed: %w", err)
	}

	if resp.Status < 200 || resp.Status >= 300 {
		return nil, fmt.Errorf("auth session failed: HTTP %d — %s", resp.Status, resp.Body)
	}

	var session SessionResponse
	if err := json.Unmarshal([]byte(resp.Body), &session); err != nil {
		return nil, fmt.Errorf("invalid session JSON: %w", err)
	}
	if session.AccessToken == "" {
		return nil, fmt.Errorf("missing accessToken in session response: %s", resp.Body)
	}

	return &session, nil
}

// fetchClientConfig retrieves client metadata.
func fetchClientConfig(cfg Config) (*ClientConfigResponse, error) {
	if cfg.ClientKey == "" {
		return nil, fmt.Errorf("CLIENT_KEY is required")
	}

	headers := map[string]string{"X-Client-Key": cfg.ClientKey}
	resp, err := doHTTP("GET", cfg.AuthBase+"/auth/skill-credit/client-config", "", "", headers)
	if err != nil {
		return nil, fmt.Errorf("client-config request failed: %w", err)
	}
	if resp.Status < 200 || resp.Status >= 300 {
		return nil, fmt.Errorf("client-config failed: HTTP %d — %s", resp.Status, resp.Body)
	}

	var config ClientConfigResponse
	if err := json.Unmarshal([]byte(resp.Body), &config); err != nil {
		return nil, fmt.Errorf("invalid client-config JSON: %w", err)
	}
	return &config, nil
}

// getToken returns a cached or fresh token.
func getToken(cfg Config) (string, error) {
	cf := cacheFile(cfg.AuthBase, cfg.ClientKey, cfg.CacheDir)
	if cached := readCachedToken(cf, cfg.MinTTLSec); cached != "" {
		return cached, nil
	}

	session, err := fetchSession(cfg)
	if err != nil {
		return "", err
	}
	writeCache(cf, session.AccessToken, session.ExpiresIn)
	return session.AccessToken, nil
}

// refreshToken bypasses cache and fetches a new token.
func refreshToken(cfg Config) (string, error) {
	cf := cacheFile(cfg.AuthBase, cfg.ClientKey, cfg.CacheDir)
	deleteCache(cf)

	session, err := fetchSession(cfg)
	if err != nil {
		return "", err
	}
	writeCache(cf, session.AccessToken, session.ExpiresIn)
	return session.AccessToken, nil
}

// requestWithRetry implements the 3-tier retry logic:
// 1. cached/fresh token → try
// 2. refresh token with same key → retry
// 3. reload .env (maybe CLIENT_KEY changed) → refresh → retry
func requestWithRetry(cfg Config, method, path, body string) (*APIResponse, error) {
	url := cfg.APIBase + path

	// 1. Try with cached or fresh token
	token, err := getToken(cfg)
	if err != nil {
		return nil, err
	}
	first, err := doHTTP(method, url, token, body, nil)
	if err != nil {
		return nil, err
	}
	if !isRetryable(first) {
		return &first, nil
	}

	// 2. Refresh token with same key
	freshToken, err := refreshToken(cfg)
	if err != nil {
		return nil, err
	}
	second, err := doHTTP(method, url, freshToken, body, nil)
	if err != nil {
		return nil, err
	}
	if !isRetryable(second) {
		return &second, nil
	}

	// 3. Reload .env — CLIENT_KEY may have changed
	oldKey := cfg.ClientKey
	cfg = reloadConfig(cfg)
	if cfg.ClientKey != oldKey {
		oldCF := cacheFile(cfg.AuthBase, oldKey, cfg.CacheDir)
		deleteCache(oldCF)
	}
	reloadedToken, err := refreshToken(cfg)
	if err != nil {
		return nil, err
	}
	third, err := doHTTP(method, url, reloadedToken, body, nil)
	if err != nil {
		return nil, err
	}
	return &third, nil
}