/**
 * Constants for Antigravity Cloud Code API integration
 * Based on: https://github.com/NoeFabris/opencode-antigravity-auth
 */

import { homedir, platform, arch } from 'os';
import { join } from 'path';
import { config } from './config.js';
import { generateSmartUserAgent, getClientVersion } from './utils/version-detector.js';

/**
 * Get the Antigravity database path based on the current platform.
 * - macOS: ~/Library/Application Support/Antigravity/...
 * - Windows: ~/AppData/Roaming/Antigravity/...
 * - Linux/other: ~/.config/Antigravity/...
 * @returns {string} Full path to the Antigravity state database
 */
function getAntigravityDbPath() {
    const home = homedir();
    switch (platform()) {
        case 'darwin':
            return join(home, 'Library/Application Support/Antigravity/User/globalStorage/state.vscdb');
        case 'win32':
            return join(home, 'AppData/Roaming/Antigravity/User/globalStorage/state.vscdb');
        default: // linux, freebsd, etc.
            return join(home, '.config/Antigravity/User/globalStorage/state.vscdb');
    }
}

/**
 * Generate platform-specific User-Agent string.
 * @returns {string} User-Agent in format "antigravity/version os/arch"
 */
export function getPlatformUserAgent() {
    return generateSmartUserAgent();
}

// IDE Type enum (numeric values as expected by Cloud Code API)
// Reference: Antigravity binary analysis - google.internal.cloud.code.v1internal.ClientMetadata.IdeType
export const IDE_TYPE = {
    UNSPECIFIED: 0,
    JETSKI: 10,        // Internal codename for Gemini CLI
    ANTIGRAVITY: 9,
    PLUGINS: 7
};

// Platform enum (as specified in Antigravity binary)
export const PLATFORM = {
    UNSPECIFIED: 0,
    DARWIN_AMD64: 1,
    DARWIN_ARM64: 2,
    LINUX_AMD64: 3,
    LINUX_ARM64: 4,
    WINDOWS_AMD64: 5
};

// Plugin type enum (as specified in Antigravity binary)
export const PLUGIN_TYPE = {
    UNSPECIFIED: 0,
    CLOUD_CODE: 1,
    GEMINI: 2
};

/**
 * Get the platform enum value based on the current OS.
 * @returns {number} Platform enum value
 */
function getPlatformEnum() {
    const os = platform();
    const architecture = arch();

    if (os === 'darwin') {
        return architecture === 'arm64' ? PLATFORM.DARWIN_ARM64 : PLATFORM.DARWIN_AMD64;
    } else if (os === 'linux') {
        return architecture === 'arm64' ? PLATFORM.LINUX_ARM64 : PLATFORM.LINUX_AMD64;
    } else if (os === 'win32') {
        return PLATFORM.WINDOWS_AMD64;
    }
    return PLATFORM.UNSPECIFIED;
}

// Centralized client metadata (used in request bodies for loadCodeAssist, onboardUser, etc.)
// Using numeric enum values as expected by the Cloud Code API
export const CLIENT_METADATA = {
    ideType: IDE_TYPE.ANTIGRAVITY,   // 6 - identifies as Antigravity client
    platform: getPlatformEnum(),      // Runtime platform detection
    pluginType: PLUGIN_TYPE.GEMINI    // 2
};

// Cloud Code API endpoints (in fallback order)
const ANTIGRAVITY_ENDPOINT_DAILY = 'https://daily-cloudcode-pa.googleapis.com';
const ANTIGRAVITY_ENDPOINT_PROD = 'https://cloudcode-pa.googleapis.com';

// Endpoint fallback order (daily → prod)
export const ANTIGRAVITY_ENDPOINT_FALLBACKS = [
    ANTIGRAVITY_ENDPOINT_DAILY,
    ANTIGRAVITY_ENDPOINT_PROD
];

// Required headers for Antigravity API requests
// Headers for general Antigravity API requests
// Strictly matches the generic 'u' method in main.js
export const ANTIGRAVITY_HEADERS = {
    'User-Agent': getPlatformUserAgent(),
    'Content-Type': 'application/json',
    'X-Client-Name': 'antigravity',
    'X-Client-Version': getClientVersion(),
    'x-goog-api-client': 'gl-node/18.18.2 fire/0.8.6 grpc/1.10.x' // Simulate Google Node.js client environment
};

// Endpoint order for loadCodeAssist (prod first)
// loadCodeAssist works better on prod for fresh/unprovisioned accounts
export const LOAD_CODE_ASSIST_ENDPOINTS = [
    ANTIGRAVITY_ENDPOINT_PROD,
    ANTIGRAVITY_ENDPOINT_DAILY
];

// Endpoint order for onboardUser (same as generateContent fallbacks)
export const ONBOARD_USER_ENDPOINTS = ANTIGRAVITY_ENDPOINT_FALLBACKS;

// Headers for loadCodeAssist API
// Matches the minimal headers seen in the binary's u() method
export const LOAD_CODE_ASSIST_HEADERS = ANTIGRAVITY_HEADERS;

// Default project ID if none can be discovered
export const DEFAULT_PROJECT_ID = 'rising-fact-p41fc';

// Configurable constants - values from config.json take precedence
export const TOKEN_REFRESH_INTERVAL_MS = config?.tokenCacheTtlMs || (5 * 60 * 1000); // From config or 5 minutes
export const REQUEST_BODY_LIMIT = config?.requestBodyLimit || '50mb';
export const ANTIGRAVITY_AUTH_PORT = 9092;
export const DEFAULT_PORT = config?.port || 8080;

// Multi-account configuration
export const ACCOUNT_CONFIG_PATH = config?.accountConfigPath || join(
    homedir(),
    '.config/antigravity-proxy/accounts.json'
);

// Usage history persistence path
export const USAGE_HISTORY_PATH = join(
    homedir(),
    '.config/antigravity-proxy/usage-history.json'
);

// Antigravity app database path (for legacy single-account token extraction)
// Uses platform-specific path detection
export const ANTIGRAVITY_DB_PATH = getAntigravityDbPath();

export const DEFAULT_COOLDOWN_MS = config?.defaultCooldownMs || (10 * 1000); // From config or 10 seconds
export const MAX_RETRIES = config?.maxRetries || 5; // From config or 5
export const MAX_EMPTY_RESPONSE_RETRIES = 2; // Max retries for empty API responses (from upstream)
export const MAX_ACCOUNTS = config?.maxAccounts || 10; // From config or 10

// Rate limit wait thresholds
export const MAX_WAIT_BEFORE_ERROR_MS = config?.maxWaitBeforeErrorMs || 120000; // From config or 2 minutes

// Retry deduplication - prevents thundering herd on concurrent rate limits
export const RATE_LIMIT_DEDUP_WINDOW_MS = config?.rateLimitDedupWindowMs || 2000; // 2 seconds
export const RATE_LIMIT_STATE_RESET_MS = config?.rateLimitStateResetMs || 120000; // 2 minutes - reset consecutive429 after inactivity
export const FIRST_RETRY_DELAY_MS = config?.firstRetryDelayMs || 1000; // Quick 1s retry on first 429
export const SWITCH_ACCOUNT_DELAY_MS = config?.switchAccountDelayMs || 5000; // Delay before switching accounts

// Consecutive failure tracking - extended cooldown after repeated failures
export const MAX_CONSECUTIVE_FAILURES = config?.maxConsecutiveFailures || 3;
export const EXTENDED_COOLDOWN_MS = config?.extendedCooldownMs || 60000; // 1 minute

// Capacity exhaustion - progressive backoff tiers for model capacity issues
export const CAPACITY_BACKOFF_TIERS_MS = config?.capacityBackoffTiersMs || [5000, 10000, 20000, 30000, 60000];
export const MAX_CAPACITY_RETRIES = config?.maxCapacityRetries || 5;

// Smart backoff by error type
export const BACKOFF_BY_ERROR_TYPE = {
    RATE_LIMIT_EXCEEDED: 30000,      // 30 seconds
    MODEL_CAPACITY_EXHAUSTED: 15000, // 15 seconds
    SERVER_ERROR: 20000,             // 20 seconds
    UNKNOWN: 60000                   // 1 minute
};

// Progressive backoff tiers for QUOTA_EXHAUSTED (60s, 5m, 30m, 2h)
export const QUOTA_EXHAUSTED_BACKOFF_TIERS_MS = [60000, 300000, 1800000, 7200000];

// Minimum backoff floor to prevent "Available in 0s" loops (matches opencode-antigravity-auth)
export const MIN_BACKOFF_MS = 2000;

// Jitter range for capacity backoff (Thundering Herd Prevention)
// Applied to MODEL_CAPACITY_EXHAUSTED to stagger client retries
export const CAPACITY_JITTER_MAX_MS = 10000; // ±5s jitter range

// Thinking model constants
export const MIN_SIGNATURE_LENGTH = 50; // Minimum valid thinking signature length

// Account selection strategies
export const SELECTION_STRATEGIES = ['sticky', 'round-robin', 'hybrid'];
export const DEFAULT_SELECTION_STRATEGY = 'hybrid';

// Strategy display labels
export const STRATEGY_LABELS = {
    'sticky': 'Sticky (Cache Optimized)',
    'round-robin': 'Round Robin (Load Balanced)',
    'hybrid': 'Hybrid (Smart Distribution)'
};

// Gemini-specific limits
export const GEMINI_MAX_OUTPUT_TOKENS = 16384;

// Gemini signature handling
// Sentinel value to skip thought signature validation when Claude Code strips the field
// See: https://ai.google.dev/gemini-api/docs/thought-signatures
export const GEMINI_SKIP_SIGNATURE = 'skip_thought_signature_validator';

// Cache TTL for Gemini thoughtSignatures (2 hours)
export const GEMINI_SIGNATURE_CACHE_TTL_MS = 2 * 60 * 60 * 1000;

// Cache TTL for model validation (5 minutes)
export const MODEL_VALIDATION_CACHE_TTL_MS = 5 * 60 * 1000;

/**
 * Get the model family from model name (dynamic detection, no hardcoded list).
 * @param {string} modelName - The model name from the request
 * @returns {'claude' | 'gemini' | 'unknown'} The model family
 */
export function getModelFamily(modelName) {
    const lower = (modelName || '').toLowerCase();
    if (lower.includes('claude')) return 'claude';
    if (lower.includes('gemini')) return 'gemini';
    return 'unknown';
}

/**
 * Check if a model supports thinking/reasoning output.
 * @param {string} modelName - The model name from the request
 * @returns {boolean} True if the model supports thinking blocks
 */
export function isThinkingModel(modelName) {
    const lower = (modelName || '').toLowerCase();
    // Claude thinking models have "thinking" in the name
    if (lower.includes('claude') && lower.includes('thinking')) return true;
    // Gemini thinking models: explicit "thinking" in name, OR gemini version 3+
    if (lower.includes('gemini')) {
        if (lower.includes('thinking')) return true;
        // Check for gemini-3 or higher (e.g., gemini-3, gemini-3.5, gemini-4, etc.)
        const versionMatch = lower.match(/gemini-(\d+)/);
        if (versionMatch && parseInt(versionMatch[1], 10) >= 3) return true;
    }
    return false;
}

// Google OAuth configuration (from opencode-antigravity-auth)
// OAuth callback port - configurable via environment variable for Windows compatibility (issue #176)
// Windows may reserve ports in range 49152-65535 for Hyper-V/WSL2/Docker, causing EACCES errors
const OAUTH_CALLBACK_PORT = parseInt(process.env.OAUTH_CALLBACK_PORT || '51121', 10);
const OAUTH_CALLBACK_FALLBACK_PORTS = [51122, 51123, 51124, 51125, 51126];

export const OAUTH_CONFIG = {
    clientId: '1071006060591-tmhssin2h21lcre235vtolojh4g403ep.apps.googleusercontent.com',
    clientSecret: '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',
    authUrl: 'https://accounts.google.com/o/oauth2/v2/auth',
    tokenUrl: 'https://oauth2.googleapis.com/token',
    userInfoUrl: 'https://www.googleapis.com/oauth2/v1/userinfo',
    callbackPort: OAUTH_CALLBACK_PORT,
    callbackFallbackPorts: OAUTH_CALLBACK_FALLBACK_PORTS,
    scopes: [
        'https://www.googleapis.com/auth/cloud-platform',
        'https://www.googleapis.com/auth/userinfo.email',
        'https://www.googleapis.com/auth/userinfo.profile',
        'https://www.googleapis.com/auth/cclog',
        'https://www.googleapis.com/auth/experimentsandconfigs'
    ]
};
export const OAUTH_REDIRECT_URI = `http://localhost:${OAUTH_CONFIG.callbackPort}/oauth-callback`;

// Minimal Antigravity system instruction (from CLIProxyAPI)
// Only includes the essential identity portion to reduce token usage and improve response quality
// Reference: GitHub issue #76, CLIProxyAPI, gcli2api
export const ANTIGRAVITY_SYSTEM_INSTRUCTION = `You are Antigravity, a powerful agentic AI coding assistant designed by the Google Deepmind team working on Advanced Agentic Coding.You are pair programming with a USER to solve their coding task. The task may require creating a new codebase, modifying or debugging an existing codebase, or simply answering a question.**Absolute paths only****Proactiveness**`;

// Model fallback mapping - maps primary model to fallback when quota exhausted
export const MODEL_FALLBACK_MAP = {
    'gemini-3.1-pro-high': 'claude-opus-4-6-thinking',
    'gemini-3.1-pro-low': 'claude-sonnet-4-6',
    'gemini-3-flash': 'claude-sonnet-4-6',
    'claude-opus-4-6-thinking': 'gemini-3.1-pro-high',
    'claude-sonnet-4-6': 'gemini-3-flash'
};

// Default test models for each family (used by test suite)
export const TEST_MODELS = {
    claude: 'claude-sonnet-4-6',
    gemini: 'gemini-3.5-flash-low'
};

// Default Claude CLI presets (used by WebUI settings)
export const DEFAULT_PRESETS = [
    {
        name: 'Claude Thinking',
        config: {
            ANTHROPIC_AUTH_TOKEN: 'test',
            ANTHROPIC_BASE_URL: 'http://localhost:8080',
            ANTHROPIC_MODEL: 'claude-opus-4-6-thinking',
            ANTHROPIC_DEFAULT_OPUS_MODEL: 'claude-opus-4-6-thinking',
            ANTHROPIC_DEFAULT_SONNET_MODEL: 'claude-sonnet-4-6',
            ANTHROPIC_DEFAULT_HAIKU_MODEL: 'claude-sonnet-4-6',
            CLAUDE_CODE_SUBAGENT_MODEL: 'claude-sonnet-4-6',
            ENABLE_EXPERIMENTAL_MCP_CLI: 'true'
        }
    },
    {
        name: 'Gemini 1M',
        config: {
            ANTHROPIC_AUTH_TOKEN: 'test',
            ANTHROPIC_BASE_URL: 'http://localhost:8080',
            ANTHROPIC_MODEL: 'gemini-3.1-pro-low',
            ANTHROPIC_DEFAULT_OPUS_MODEL: 'gemini-3.1-pro-low',
            ANTHROPIC_DEFAULT_SONNET_MODEL: 'gemini-3.5-flash-low',
            ANTHROPIC_DEFAULT_HAIKU_MODEL: 'gemini-3.5-flash-low',
            CLAUDE_CODE_SUBAGENT_MODEL: 'gemini-3.5-flash-low',
            ENABLE_EXPERIMENTAL_MCP_CLI: 'true'
        }
    }
];

/**
 * Built-in server configuration presets.
 * Each preset has builtIn: true and cannot be deleted by users.
 */
export const DEFAULT_SERVER_PRESETS = [
    {
        name: 'Default (3-5 Accounts)',
        builtIn: true,
        descriptionKey: 'presetDefaultDesc',
        config: {
            maxRetries: 5,
            retryBaseMs: 1000,
            retryMaxMs: 30000,
            defaultCooldownMs: 10000,
            maxWaitBeforeErrorMs: 120000,
            maxAccounts: 10,
            globalQuotaThreshold: 0,
            rateLimitDedupWindowMs: 2000,
            maxConsecutiveFailures: 3,
            extendedCooldownMs: 60000,
            maxCapacityRetries: 5,
            switchAccountDelayMs: 5000,
            capacityBackoffTiersMs: [5000, 10000, 20000, 30000, 60000],
            accountSelection: {
                strategy: 'hybrid',
                healthScore: {
                    initial: 70,
                    successReward: 1,
                    rateLimitPenalty: -10,
                    failurePenalty: -20,
                    recoveryPerHour: 10,
                    minUsable: 50,
                    maxScore: 100
                },
                tokenBucket: {
                    maxTokens: 50,
                    tokensPerMinute: 6,
                    initialTokens: 50
                },
                quota: {
                    lowThreshold: 0.10,
                    criticalThreshold: 0.05,
                    staleMs: 300000
                },
                weights: {
                    health: 2,
                    tokens: 5,
                    quota: 3,
                    lru: 0.1
                }
            }
        }
    },
    {
        name: 'Many Accounts (10+)',
        builtIn: true,
        descriptionKey: 'presetManyAccountsDesc',
        config: {
            maxRetries: 3,
            retryBaseMs: 500,
            retryMaxMs: 15000,
            defaultCooldownMs: 5000,
            maxWaitBeforeErrorMs: 60000,
            maxAccounts: 50,
            globalQuotaThreshold: 0.10,
            rateLimitDedupWindowMs: 1000,
            maxConsecutiveFailures: 2,
            extendedCooldownMs: 30000,
            maxCapacityRetries: 3,
            switchAccountDelayMs: 3000,
            capacityBackoffTiersMs: [3000, 6000, 12000, 20000, 40000],
            accountSelection: {
                strategy: 'hybrid',
                healthScore: {
                    initial: 70,
                    successReward: 1,
                    rateLimitPenalty: -15,
                    failurePenalty: -25,
                    recoveryPerHour: 5,
                    minUsable: 40,
                    maxScore: 100
                },
                tokenBucket: {
                    maxTokens: 30,
                    tokensPerMinute: 8,
                    initialTokens: 30
                },
                quota: {
                    lowThreshold: 0.15,
                    criticalThreshold: 0.05,
                    staleMs: 180000
                },
                weights: {
                    health: 5,
                    tokens: 2,
                    quota: 3,
                    lru: 0.01
                }
            }
        }
    },
    {
        name: 'Conservative',
        builtIn: true,
        descriptionKey: 'presetConservativeDesc',
        config: {
            maxRetries: 8,
            retryBaseMs: 2000,
            retryMaxMs: 60000,
            defaultCooldownMs: 20000,
            maxWaitBeforeErrorMs: 240000,
            maxAccounts: 10,
            globalQuotaThreshold: 0.20,
            rateLimitDedupWindowMs: 3000,
            maxConsecutiveFailures: 5,
            extendedCooldownMs: 120000,
            maxCapacityRetries: 8,
            switchAccountDelayMs: 8000,
            capacityBackoffTiersMs: [8000, 15000, 30000, 45000, 90000],
            accountSelection: {
                strategy: 'sticky',
                healthScore: {
                    initial: 80,
                    successReward: 2,
                    rateLimitPenalty: -5,
                    failurePenalty: -10,
                    recoveryPerHour: 3,
                    minUsable: 50,
                    maxScore: 100
                },
                tokenBucket: {
                    maxTokens: 80,
                    tokensPerMinute: 4,
                    initialTokens: 80
                },
                quota: {
                    lowThreshold: 0.20,
                    criticalThreshold: 0.10,
                    staleMs: 300000
                },
                weights: {
                    health: 3,
                    tokens: 4,
                    quota: 2,
                    lru: 0.05
                }
            }
        }
    }
];

export default {
    IDE_TYPE,
    PLATFORM,
    PLUGIN_TYPE,
    CLIENT_METADATA,
    ANTIGRAVITY_ENDPOINT_FALLBACKS,
    ANTIGRAVITY_HEADERS,
    LOAD_CODE_ASSIST_ENDPOINTS,
    ONBOARD_USER_ENDPOINTS,
    LOAD_CODE_ASSIST_HEADERS,
    DEFAULT_PROJECT_ID,
    TOKEN_REFRESH_INTERVAL_MS,
    REQUEST_BODY_LIMIT,
    ANTIGRAVITY_AUTH_PORT,
    DEFAULT_PORT,
    ACCOUNT_CONFIG_PATH,
    ANTIGRAVITY_DB_PATH,
    DEFAULT_COOLDOWN_MS,
    MAX_RETRIES,
    MAX_EMPTY_RESPONSE_RETRIES,
    MAX_ACCOUNTS,
    MAX_WAIT_BEFORE_ERROR_MS,
    RATE_LIMIT_DEDUP_WINDOW_MS,
    RATE_LIMIT_STATE_RESET_MS,
    FIRST_RETRY_DELAY_MS,
    SWITCH_ACCOUNT_DELAY_MS,
    MAX_CONSECUTIVE_FAILURES,
    EXTENDED_COOLDOWN_MS,
    CAPACITY_BACKOFF_TIERS_MS,
    MAX_CAPACITY_RETRIES,
    BACKOFF_BY_ERROR_TYPE,
    QUOTA_EXHAUSTED_BACKOFF_TIERS_MS,
    MIN_BACKOFF_MS,
    CAPACITY_JITTER_MAX_MS,
    MIN_SIGNATURE_LENGTH,
    GEMINI_MAX_OUTPUT_TOKENS,
    GEMINI_SKIP_SIGNATURE,
    GEMINI_SIGNATURE_CACHE_TTL_MS,
    MODEL_VALIDATION_CACHE_TTL_MS,
    getModelFamily,
    isThinkingModel,
    OAUTH_CONFIG,
    OAUTH_REDIRECT_URI,
    STRATEGY_LABELS,
    MODEL_FALLBACK_MAP,
    TEST_MODELS,
    DEFAULT_PRESETS,
    DEFAULT_SERVER_PRESETS,
    ANTIGRAVITY_SYSTEM_INSTRUCTION
};