package main

import (
	"fmt"
	"math/big"
	"os"
	"strconv"
	"strings"
	"time"
)

type Config struct {
	ListenAddr               string
	DBPath                   string
	AllowedOrigin            string
	DeploymentClass          string
	MemberPollIntervalSec    int
	IntentTTL                time.Duration
	QuoteTTL                 time.Duration
	WalletSessionTTL         time.Duration
	RequireWalletSession     bool
	InstallTokenTTL          time.Duration
	LeaseTTL                 time.Duration
	OfflineRenewTTL          time.Duration
	ChainID                  int64
	DomainName               string
	VerifyingContract        string
	MembershipContract       string
	EntitlementContract      string
	MintCurrency             string
	MintAmountAtomic         string
	MintDecimals             int
	ChainRPCURL              string
	RequireOnchainTxVerify   bool
	GovernanceRuntimeVersion string
	GovernancePackageURL     string
	GovernancePackageHash    string
	GovernancePackageSig     string
	GovernanceSignerKeyID    string
	GovernancePolicyHash     string
	GovernanceRolloutChannel string
}

func loadConfig() Config {
	return Config{
		ListenAddr:               env("SECRET_API_LISTEN_ADDR", ":8080"),
		DBPath:                   env("SECRET_API_DB_PATH", "./secret.db"),
		AllowedOrigin:            env("SECRET_API_ALLOWED_ORIGIN", "https://edut.ai"),
		DeploymentClass:          normalizeDeploymentClass(env("SECRET_API_DEPLOYMENT_CLASS", "development")),
		MemberPollIntervalSec:    envInt("SECRET_API_MEMBER_POLL_INTERVAL_SECONDS", 30),
		IntentTTL:                time.Duration(envInt("SECRET_API_INTENT_TTL_SECONDS", 900)) * time.Second,
		QuoteTTL:                 time.Duration(envInt("SECRET_API_QUOTE_TTL_SECONDS", 900)) * time.Second,
		WalletSessionTTL:         time.Duration(envInt("SECRET_API_WALLET_SESSION_TTL_SECONDS", 2592000)) * time.Second,
		RequireWalletSession:     envBool("SECRET_API_REQUIRE_WALLET_SESSION", true),
		InstallTokenTTL:          time.Duration(envInt("SECRET_API_INSTALL_TOKEN_TTL_SECONDS", 900)) * time.Second,
		LeaseTTL:                 time.Duration(envInt("SECRET_API_LEASE_TTL_SECONDS", 3600)) * time.Second,
		OfflineRenewTTL:          time.Duration(envInt("SECRET_API_OFFLINE_RENEW_TTL_SECONDS", 2592000)) * time.Second,
		ChainID:                  int64(envInt("SECRET_API_CHAIN_ID", 84532)),
		DomainName:               env("SECRET_API_DOMAIN_NAME", "EDUT Designation"),
		VerifyingContract:        strings.ToLower(env("SECRET_API_VERIFYING_CONTRACT", "0x0000000000000000000000000000000000000000")),
		MembershipContract:       strings.ToLower(env("SECRET_API_MEMBERSHIP_CONTRACT", "0x0000000000000000000000000000000000000000")),
		EntitlementContract:      strings.ToLower(env("SECRET_API_ENTITLEMENT_CONTRACT", "0x0000000000000000000000000000000000000000")),
		MintCurrency:             strings.ToUpper(env("SECRET_API_MINT_CURRENCY", "USDC")),
		MintAmountAtomic:         env("SECRET_API_MINT_AMOUNT_ATOMIC", "100000000"),
		MintDecimals:             envInt("SECRET_API_MINT_DECIMALS", 6),
		ChainRPCURL:              env("SECRET_API_CHAIN_RPC_URL", ""),
		RequireOnchainTxVerify:   loadRequireOnchainTxVerify(),
		GovernanceRuntimeVersion: env("SECRET_API_GOV_RUNTIME_VERSION", "0.1.0"),
		GovernancePackageURL:     env("SECRET_API_GOV_PACKAGE_URL", "https://cdn.edut.ai/governance/edutd-0.1.0.tar.gz"),
		GovernancePackageHash:    strings.ToLower(env("SECRET_API_GOV_PACKAGE_HASH", "sha256:pending")),
		GovernancePackageSig:     env("SECRET_API_GOV_PACKAGE_SIGNATURE", "pending"),
		GovernanceSignerKeyID:    env("SECRET_API_GOV_SIGNER_KEY_ID", "edut-signer-1"),
		GovernancePolicyHash:     strings.ToLower(env("SECRET_API_GOV_POLICY_HASH", "sha256:pending")),
		GovernanceRolloutChannel: strings.ToLower(env("SECRET_API_GOV_ROLLOUT_CHANNEL", "stable")),
	}
}

func (c Config) Validate() error {
	if c.ChainID <= 0 {
		return fmt.Errorf("SECRET_API_CHAIN_ID must be positive")
	}
	currency := strings.ToUpper(strings.TrimSpace(c.MintCurrency))
	switch currency {
	case "USDC":
		if c.MintDecimals != 6 {
			return fmt.Errorf("SECRET_API_MINT_DECIMALS must be 6 for USDC")
		}
	case "ETH":
		if c.MintDecimals != 18 {
			return fmt.Errorf("SECRET_API_MINT_DECIMALS must be 18 for ETH")
		}
	default:
		return fmt.Errorf("SECRET_API_MINT_CURRENCY must be USDC or ETH")
	}
	amountRaw := strings.TrimSpace(c.MintAmountAtomic)
	amount, ok := new(big.Int).SetString(amountRaw, 10)
	if !ok || amount.Sign() <= 0 {
		return fmt.Errorf("SECRET_API_MINT_AMOUNT_ATOMIC must be a positive base-10 integer")
	}
	if c.WalletSessionTTL <= 0 {
		return fmt.Errorf("SECRET_API_WALLET_SESSION_TTL_SECONDS must be positive")
	}
	if isProductionDeploymentClass(c.DeploymentClass) && !c.RequireOnchainTxVerify {
		return fmt.Errorf("production deployment requires SECRET_API_REQUIRE_ONCHAIN_TX_VERIFICATION=true")
	}
	if c.RequireOnchainTxVerify && strings.TrimSpace(c.ChainRPCURL) == "" {
		return fmt.Errorf("SECRET_API_REQUIRE_ONCHAIN_TX_VERIFICATION requires SECRET_API_CHAIN_RPC_URL")
	}
	return nil
}

func loadRequireOnchainTxVerify() bool {
	if raw, ok := os.LookupEnv("SECRET_API_REQUIRE_ONCHAIN_TX_VERIFICATION"); ok {
		if strings.TrimSpace(raw) != "" {
			return parseBool(raw, false)
		}
	}
	return isProductionDeploymentClass(env("SECRET_API_DEPLOYMENT_CLASS", "development"))
}

func env(key, fallback string) string {
	if v := strings.TrimSpace(os.Getenv(key)); v != "" {
		return v
	}
	return fallback
}

func envInt(key string, fallback int) int {
	raw := strings.TrimSpace(os.Getenv(key))
	if raw == "" {
		return fallback
	}
	value, err := strconv.Atoi(raw)
	if err != nil {
		return fallback
	}
	return value
}

func envBool(key string, fallback bool) bool {
	raw := strings.ToLower(strings.TrimSpace(os.Getenv(key)))
	if raw == "" {
		return fallback
	}
	return parseBool(raw, fallback)
}

func parseBool(raw string, fallback bool) bool {
	raw = strings.ToLower(strings.TrimSpace(raw))
	switch raw {
	case "1", "true", "yes", "on":
		return true
	case "0", "false", "no", "off":
		return false
	default:
		return fallback
	}
}

func normalizeDeploymentClass(value string) string {
	v := strings.ToLower(strings.TrimSpace(value))
	switch v {
	case "prod", "production":
		return "production"
	case "staging", "stage":
		return "staging"
	case "dev", "development":
		return "development"
	default:
		return "development"
	}
}

func isProductionDeploymentClass(value string) bool {
	return normalizeDeploymentClass(value) == "production"
}