package version

import (
	"fmt"
	"time"
)

// Version coordination for Server Authority model
// The server is the single source of truth for all version information
//
// Version Sources:
// - Agent versions: Compiled into agent via ldflags during build (see agent/internal/version)
// - Server versions: Compiled into server via ldflags during build (injected below)
// - Database: agents table stores agent_version at registration

// Build-time injected version information (SERVER AUTHORITY)
// Injected by build script during server compilation
var (
	AgentVersion    = "dev" // Server's agent version (format: 0.1.27)
	ConfigVersion   = "dev" // Config schema version (format: 3)
	MinAgentVersion = "dev" // Minimum supported agent version
)

// CurrentVersions holds the authoritative version information for API responses
type CurrentVersions struct {
	AgentVersion    string `json:"agent_version"`    // e.g., "0.1.27"
	ConfigVersion   string `json:"config_version"`   // e.g., "3"
	MinAgentVersion string `json:"min_agent_version"` // e.g., "0.1.22"
	BuildTime       time.Time `json:"build_time"`
}

// GetCurrentVersions returns the current version information
// Version is compiled into the server binary at build time via ldflags
func GetCurrentVersions() CurrentVersions {
	// Build-time injection allows version updates without code changes
	// See Dockerfile for injection via: -ldflags "-X .../version.AgentVersion=0.1.27"
	return CurrentVersions{
		AgentVersion:    AgentVersion,
		ConfigVersion:   ConfigVersion,
		MinAgentVersion: MinAgentVersion,
		BuildTime:       time.Now(),
	}
}

// ExtractConfigVersionFromAgent extracts config version from agent version
// Agent version format: v0.1.23.6 where fourth octet maps to config version
func ExtractConfigVersionFromAgent(agentVersion string) string {
	// Strip 'v' prefix if present
	cleanVersion := agentVersion
	if len(cleanVersion) > 0 && cleanVersion[0] == 'v' {
		cleanVersion = cleanVersion[1:]
	}

	// Split version parts
	parts := fmt.Sprintf("%s", cleanVersion)
	if len(parts) >= 1 {
		// For now, use the last octet as config version
		// v0.1.23 -> "3" (last digit)
		lastChar := parts[len(parts)-1:]
		return lastChar
	}

	// Default fallback
	return "3"
}

// ValidateAgentVersion checks if an agent version is compatible
func ValidateAgentVersion(agentVersion string) error {
	current := GetCurrentVersions()

	// Check minimum version
	if agentVersion < current.MinAgentVersion {
		return fmt.Errorf("agent version %s is below minimum %s", agentVersion, current.MinAgentVersion)
	}

	return nil
}

// GetBuildFlags returns the ldflags to inject versions into agent builds
func GetBuildFlags() []string {
	versions := GetCurrentVersions()
	return []string{
		fmt.Sprintf("-X github.com/Fimeg/RedFlag/aggregator-agent/internal/version.Version=%s", versions.AgentVersion),
		fmt.Sprintf("-X github.com/Fimeg/RedFlag/aggregator-agent/internal/version.ConfigVersion=%s", versions.ConfigVersion),
		fmt.Sprintf("-X github.com/Fimeg/RedFlag/aggregator-agent/internal/version.BuildTime=%s", versions.BuildTime.Format(time.RFC3339)),
	}
}