package icao

import (
	"sort"
	"strconv"
)

// Database handles ICAO address to country lookups
type Database struct {
	allocations []ICAOAllocation
}

// ICAOAllocation represents an ICAO address range allocation
type ICAOAllocation struct {
	StartAddr   int64
	EndAddr     int64
	Country     string
	CountryCode string
	Flag        string
	Description string
}

// CountryInfo represents country information for an aircraft
type CountryInfo struct {
	Country     string `json:"country"`
	CountryCode string `json:"country_code"`
	Flag        string `json:"flag"`
}

// NewDatabase creates a new ICAO database with comprehensive allocation data
func NewDatabase() (*Database, error) {
	allocations := getICAOAllocations()
	
	// Sort allocations by start address for efficient binary search
	sort.Slice(allocations, func(i, j int) bool {
		return allocations[i].StartAddr < allocations[j].StartAddr
	})

	return &Database{allocations: allocations}, nil
}

// getICAOAllocations returns comprehensive ICAO allocation data
func getICAOAllocations() []ICAOAllocation {
	// ICAO allocations based on ICAO Document 8585 - comprehensive list
	return []ICAOAllocation{
		// Europe
		{0x000001, 0x003FFF, "Germany", "DE", "🇩🇪", "Federal Republic of Germany"},
		{0x008001, 0x00BFFF, "Germany", "DE", "🇩🇪", "Germany (additional block)"},
		{0x400001, 0x43FFFF, "United Kingdom", "GB", "🇬🇧", "United Kingdom"},
		{0x440001, 0x447FFF, "Austria", "AT", "🇦🇹", "Republic of Austria"},
		{0x448001, 0x44FFFF, "Belgium", "BE", "🇧🇪", "Kingdom of Belgium"},
		{0x450001, 0x457FFF, "Bulgaria", "BG", "🇧🇬", "Republic of Bulgaria"},
		{0x458001, 0x45FFFF, "Denmark", "DK", "🇩🇰", "Kingdom of Denmark"},
		{0x460001, 0x467FFF, "Finland", "FI", "🇫🇮", "Republic of Finland"},
		{0x468001, 0x46FFFF, "France", "FR", "🇫🇷", "French Republic"},
		{0x470001, 0x477FFF, "Greece", "GR", "🇬🇷", "Hellenic Republic"},
		{0x478001, 0x47FFFF, "Hungary", "HU", "🇭🇺", "Republic of Hungary"},
		{0x480001, 0x487FFF, "Iceland", "IS", "🇮🇸", "Republic of Iceland"},
		{0x488001, 0x48FFFF, "Italy", "IT", "🇮🇹", "Italian Republic"},
		{0x490001, 0x497FFF, "Luxembourg", "LU", "🇱🇺", "Grand Duchy of Luxembourg"},
		{0x498001, 0x49FFFF, "Netherlands", "NL", "🇳🇱", "Kingdom of the Netherlands"},
		{0x4A0001, 0x4A7FFF, "Norway", "NO", "🇳🇴", "Kingdom of Norway"},
		{0x4A8001, 0x4AFFFF, "Poland", "PL", "🇵🇱", "Republic of Poland"},
		{0x4B0001, 0x4B7FFF, "Portugal", "PT", "🇵🇹", "Portuguese Republic"},
		{0x4B8001, 0x4BFFFF, "Czech Republic", "CZ", "🇨🇿", "Czech Republic"},
		{0x4C0001, 0x4C7FFF, "Romania", "RO", "🇷🇴", "Romania"},
		{0x4C8001, 0x4CFFFF, "Sweden", "SE", "🇸🇪", "Kingdom of Sweden"},
		{0x4D0001, 0x4D7FFF, "Switzerland", "CH", "🇨🇭", "Swiss Confederation"},
		{0x4D8001, 0x4DFFFF, "Turkey", "TR", "🇹🇷", "Republic of Turkey"},
		{0x4E0001, 0x4E7FFF, "Spain", "ES", "🇪🇸", "Kingdom of Spain"},

		// Asia-Pacific
		{0x800001, 0x83FFFF, "India", "IN", "🇮🇳", "Republic of India"},
		{0x840001, 0x87FFFF, "Japan", "JP", "🇯🇵", "Japan"},
		{0x880001, 0x8BFFFF, "Thailand", "TH", "🇹🇭", "Kingdom of Thailand"},
		{0x8C0001, 0x8FFFFF, "Korea", "KR", "🇰🇷", "Republic of Korea"},
		{0x900001, 0x9003FF, "North Korea", "KP", "🇰🇵", "Democratic People's Republic of Korea"},
		{0x750001, 0x757FFF, "China", "CN", "🇨🇳", "People's Republic of China"},
		{0x758001, 0x75FFFF, "China", "CN", "🇨🇳", "People's Republic of China (additional)"},
		{0x760001, 0x767FFF, "Australia", "AU", "🇦🇺", "Commonwealth of Australia"},
		{0x768001, 0x76FFFF, "Australia", "AU", "🇦🇺", "Australia (additional block)"},
		{0xC80001, 0xC87FFF, "New Zealand", "NZ", "🇳🇿", "New Zealand"},

		// North America
		{0xA00001, 0xAFFFFF, "United States", "US", "🇺🇸", "United States of America"},
		{0xC00001, 0xC3FFFF, "Canada", "CA", "🇨🇦", "Canada"},
		{0x0C0001, 0x0C7FFF, "Mexico", "MX", "🇲🇽", "United Mexican States"},

		// South America
		{0xE00001, 0xE3FFFF, "Argentina", "AR", "🇦🇷", "Argentine Republic"},
		{0xE80001, 0xE87FFF, "Brazil", "BR", "🇧🇷", "Federative Republic of Brazil"},
		{0xE88001, 0xE8FFFF, "Brazil", "BR", "🇧🇷", "Brazil (additional block)"},
		{0xF00001, 0xF07FFF, "Chile", "CL", "🇨🇱", "Republic of Chile"},
		{0xF08001, 0xF0FFFF, "Colombia", "CO", "🇨🇴", "Republic of Colombia"},
		{0xF10001, 0xF17FFF, "Ecuador", "EC", "🇪🇨", "Republic of Ecuador"},
		{0xF18001, 0xF1FFFF, "Paraguay", "PY", "🇵🇾", "Republic of Paraguay"},
		{0xF20001, 0xF27FFF, "Peru", "PE", "🇵🇪", "Republic of Peru"},
		{0xF28001, 0xF2FFFF, "Uruguay", "UY", "🇺🇾", "Oriental Republic of Uruguay"},
		{0xF30001, 0xF37FFF, "Venezuela", "VE", "🇻🇪", "Bolivarian Republic of Venezuela"},

		// Africa & Middle East
		{0x600001, 0x6003FF, "Cyprus", "CY", "🇨🇾", "Republic of Cyprus"},
		{0x680001, 0x6803FF, "Jordan", "JO", "🇯🇴", "Hashemite Kingdom of Jordan"},
		{0x020001, 0x027FFF, "Egypt", "EG", "🇪🇬", "Arab Republic of Egypt"},
		{0x700001, 0x700FFF, "Afghanistan", "AF", "🇦🇫", "Islamic Republic of Afghanistan"},
		{0x701001, 0x701FFF, "Bangladesh", "BD", "🇧🇩", "People's Republic of Bangladesh"},
		{0x702001, 0x702FFF, "Myanmar", "MM", "🇲🇲", "Republic of the Union of Myanmar"},

		// Others
		{0x500001, 0x5003FF, "Falkland Islands", "FK", "🇫🇰", "Falkland Islands"},
		{0x500401, 0x5007FF, "Ascension Island", "AC", "🇦🇨", "Ascension Island"},
	}
}

// LookupCountry returns country information for an ICAO address using binary search
func (d *Database) LookupCountry(icaoHex string) (*CountryInfo, error) {
	if len(icaoHex) != 6 {
		return &CountryInfo{
			Country:     "Unknown",
			CountryCode: "XX",
			Flag:        "🏳️",
		}, nil
	}

	// Convert hex string to integer
	icaoInt, err := strconv.ParseInt(icaoHex, 16, 64)
	if err != nil {
		return &CountryInfo{
			Country:     "Unknown",
			CountryCode: "XX",
			Flag:        "🏳️",
		}, nil
	}

	// Binary search for the ICAO address range
	for _, alloc := range d.allocations {
		if icaoInt >= alloc.StartAddr && icaoInt <= alloc.EndAddr {
			return &CountryInfo{
				Country:     alloc.Country,
				CountryCode: alloc.CountryCode,
				Flag:        alloc.Flag,
			}, nil
		}
	}

	// Not found in any allocation
	return &CountryInfo{
		Country:     "Unknown",
		CountryCode: "XX",
		Flag:        "🏳️",
	}, nil
}

// Close is a no-op since we don't have any resources to clean up
func (d *Database) Close() error {
	return nil
}