/**
 * Lookup Utilities - Reusable functions for aircraft and airport lookups
 */

/**
 * Format aircraft registration based on UK rules
 * - 5 alphabetic chars: add hyphen after first char (GIVYY -> G-IVYY)
 * - Otherwise: just uppercase (N123AD -> N123AD)
 */
function formatAircraftRegistration(input) {
    if (!input) return '';
    
    const cleaned = input.trim().toUpperCase();
    
    // If exactly 5 characters and all alphabetic, add hyphen
    if (cleaned.length === 5 && /^[A-Z]{5}$/.test(cleaned)) {
        return cleaned[0] + '-' + cleaned.substring(1);
    }
    
    // Otherwise just return uppercase version
    return cleaned;
}

/**
 * Creates a reusable lookup handler
 * @param {string} fieldId - ID of the input field
 * @param {string} resultsId - ID of the results container
 * @param {function} selectCallback - Function to call when item is selected
 * @param {object} options - Additional options (minLength, debounceMs, etc.)
 */
function createLookup(fieldId, resultsId, selectCallback, options = {}) {
    const defaults = {
        minLength: 2,
        debounceMs: 300,
        isAirport: false,
        isAircraft: false,
        maxResults: 10
    };
    const config = { ...defaults, ...options };
    let debounceTimeout;
    let currentResults = [];
    let selectedIndex = -1;
    let keydownHandlerAttached = false;

    const lookup = {
        // Main handler called by oninput
        handle: (value) => {
            clearTimeout(debounceTimeout);
            selectedIndex = -1; // Reset selection on new input
            
            if (!value || value.trim().length < config.minLength) {
                lookup.clear();
                return;
            }

            lookup.showSearching();
            debounceTimeout = setTimeout(() => {
                lookup.perform(value);
            }, config.debounceMs);
        },

        // Attach keyboard handler once (for airport lookups)
        attachKeyboardHandler: () => {
            if (config.isAirport && !keydownHandlerAttached) {
                try {
                    const inputField = document.getElementById(fieldId);
                    if (inputField) {
                        inputField.addEventListener('keydown', (e) => lookup.handleKeydown(e));
                        keydownHandlerAttached = true;
                    }
                } catch (error) {
                    console.error('Error attaching keyboard handler:', error);
                }
            }
        },

        // Handle keyboard events
        handleKeydown: (event) => {
            if (!currentResults || currentResults.length === 0) return;
            
            if (event.key === 'ArrowDown') {
                event.preventDefault();
                selectedIndex = Math.min(selectedIndex + 1, currentResults.length - 1);
                lookup.updateSelection();
            } else if (event.key === 'ArrowUp') {
                event.preventDefault();
                selectedIndex = Math.max(selectedIndex - 1, -1);
                lookup.updateSelection();
            } else if (event.key === 'Enter') {
                event.preventDefault();
                if (selectedIndex >= 0 && currentResults[selectedIndex]) {
                    lookup.selectResult(currentResults[selectedIndex]);
                } else if (currentResults.length === 1) {
                    // Auto-select if only one result and Enter pressed
                    lookup.selectResult(currentResults[0]);
                }
            } else if (event.key === 'Escape') {
                lookup.clear();
                selectedIndex = -1;
            }
        },

        // Update visual selection
        updateSelection: () => {
            const resultsDiv = document.getElementById(resultsId);
            if (!resultsDiv) return;
            
            const options = resultsDiv.querySelectorAll('.lookup-option');
            options.forEach((opt, idx) => {
                if (idx === selectedIndex) {
                    opt.classList.add('lookup-option-selected');
                    opt.scrollIntoView({ block: 'nearest' });
                } else {
                    opt.classList.remove('lookup-option-selected');
                }
            });
        },

        // Select a result item
        selectResult: (item) => {
            const field = document.getElementById(fieldId);
            if (field) {
                field.value = item.icao;
            }
            lookup.clear();
            currentResults = [];
            selectedIndex = -1;
            if (selectCallback) selectCallback(item.icao);
        },

        // Perform the lookup
        perform: async (searchTerm) => {
            try {
                const cleanInput = searchTerm.trim();
                let endpoint;

                if (config.isAircraft) {
                    const cleaned = cleanInput.replace(/[^a-zA-Z0-9]/g, '').toUpperCase();
                    if (cleaned.length < config.minLength) {
                        lookup.clear();
                        return;
                    }
                    endpoint = `/api/v1/aircraft/lookup/${cleaned}`;
                } else if (config.isAirport) {
                    endpoint = `/api/v1/airport/lookup/${encodeURIComponent(cleanInput)}`;
                }

                if (!endpoint) throw new Error('Invalid lookup type');

                const response = await authenticatedFetch(endpoint);
                if (!response.ok) throw new Error('Lookup failed');

                const results = await response.json();
                lookup.display(results, cleanInput);
            } catch (error) {
                console.error('Lookup error:', error);
                lookup.showError();
            }
        },

        // Display results
        display: (results, searchTerm) => {
            const resultsDiv = document.getElementById(resultsId);
            
            if (config.isAircraft) {
                // Aircraft lookup: auto-populate on single match, format input on no match
                if (!results || results.length === 0) {
                    // Format the aircraft registration and auto-populate
                    const formatted = formatAircraftRegistration(searchTerm);
                    const field = document.getElementById(fieldId);
                    if (field) {
                        field.value = formatted;
                    }
                    resultsDiv.innerHTML = ''; // Clear results, field is auto-populated
                } else if (results.length === 1) {
                    // Single match - auto-populate
                    const aircraft = results[0];
                    resultsDiv.innerHTML = `
                        <div class="aircraft-match">
                            ✓ ${aircraft.manufacturer_name || ''} ${aircraft.model || aircraft.type_code || ''}
                        </div>
                    `;
                    
                    // Auto-populate the form fields
                    const field = document.getElementById(fieldId);
                    if (field) field.value = aircraft.registration;
                    
                    // Also populate type field
                    let typeFieldId;
                    if (fieldId === 'ac_reg') {
                        typeFieldId = 'ac_type';
                    } else if (fieldId === 'local_registration') {
                        typeFieldId = 'local_type';
                    } else if (fieldId === 'book_in_registration') {
                        typeFieldId = 'book_in_type';
                    } else if (fieldId === 'overflight_registration') {
                        typeFieldId = 'overflight_type';
                    }
                    
                    if (typeFieldId) {
                        const typeField = document.getElementById(typeFieldId);
                        if (typeField) typeField.value = aircraft.type_code || '';
                    }
                } else {
                    // Multiple matches
                    resultsDiv.innerHTML = `
                        <div class="aircraft-no-match">
                            Multiple matches found (${results.length}) - please be more specific
                        </div>
                    `;
                }
            } else {
                // Airport lookup: show list of options with keyboard navigation
                if (!results || results.length === 0) {
                    resultsDiv.innerHTML = '<div class="lookup-no-match">No matches found - will use as entered</div>';
                    currentResults = [];
                    return;
                }

                currentResults = results.slice(0, config.maxResults);
                selectedIndex = -1; // Reset selection when showing new results
                
                const matchText = currentResults.length === 1 ? 'Match found - press ENTER or click to select:' : 'Multiple matches found - use arrow keys and ENTER to select:';
                
                let html = `<div class="lookup-no-match" style="margin-bottom: 0.5rem;">${matchText}</div><div class="lookup-list">`;
                
                currentResults.forEach((item, idx) => {
                    html += `
                        <div class="lookup-option" onclick="lookupManager.selectItem('${resultsId}', '${fieldId}', '${item.icao}')">
                            <div class="lookup-code">${item.icao}</div>
                            <div class="lookup-name">${item.name || '-'}</div>
                            ${item.city ? `<div class="lookup-location">${item.city}, ${item.country}</div>` : ''}
                        </div>
                    `;
                });
                
                html += '</div>';
                resultsDiv.innerHTML = html;
                
                // Attach keyboard handler (only once per lookup instance)
                lookup.attachKeyboardHandler();
            }
        },

        // Show searching state
        showSearching: () => {
            const resultsDiv = document.getElementById(resultsId);
            if (resultsDiv) {
                resultsDiv.innerHTML = '<div class="lookup-searching">Searching...</div>';
            }
        },

        // Show error state
        showError: () => {
            const resultsDiv = document.getElementById(resultsId);
            if (resultsDiv) {
                resultsDiv.innerHTML = '<div class="lookup-no-match">Lookup failed - will use as entered</div>';
            }
        },

        // Clear results
        clear: () => {
            const resultsDiv = document.getElementById(resultsId);
            if (resultsDiv) {
                resultsDiv.innerHTML = '';
            }
        },

        // Set the selected value
        setValue: (value) => {
            const field = document.getElementById(fieldId);
            if (field) {
                field.value = value;
            }
            lookup.clear();
            if (selectCallback) selectCallback(value);
        }
    };

    return lookup;
}

/**
 * Global lookup manager for all lookups on the page
 */
const lookupManager = {
    lookups: {},

    // Register a lookup instance
    register: (name, lookup) => {
        lookupManager.lookups[name] = lookup;
    },

    // Generic item selection handler
    selectItem: (resultsId, fieldId, itemCode) => {
        const field = document.getElementById(fieldId);
        if (field) {
            field.value = itemCode;
        }
        const resultsDiv = document.getElementById(resultsId);
        if (resultsDiv) {
            resultsDiv.innerHTML = '';
        }
    }
};

// Initialize all lookups when page loads
function initializeLookups() {
    // Create reusable lookup instances
    const arrivalAirportLookup = createLookup(
        'in_from',
        'arrival-airport-lookup-results',
        null,
        { isAirport: true, minLength: 2 }
    );
    lookupManager.register('arrival-airport', arrivalAirportLookup);

    const departureAirportLookup = createLookup(
        'out_to',
        'departure-airport-lookup-results',
        null,
        { isAirport: true, minLength: 2 }
    );
    lookupManager.register('departure-airport', departureAirportLookup);

    const localOutToLookup = createLookup(
        'local_out_to',
        'local-out-to-lookup-results',
        null,
        { isAirport: true, minLength: 2 }
    );
    lookupManager.register('local-out-to', localOutToLookup);

    const aircraftLookup = createLookup(
        'ac_reg',
        'aircraft-lookup-results',
        null,
        { isAircraft: true, minLength: 4, debounceMs: 300 }
    );
    lookupManager.register('aircraft', aircraftLookup);

    const localAircraftLookup = createLookup(
        'local_registration',
        'local-aircraft-lookup-results',
        null,
        { isAircraft: true, minLength: 4, debounceMs: 300 }
    );
    lookupManager.register('local-aircraft', localAircraftLookup);

    const bookInAircraftLookup = createLookup(
        'book_in_registration',
        'book-in-aircraft-lookup-results',
        null,
        { isAircraft: true, minLength: 4, debounceMs: 300 }
    );
    lookupManager.register('book-in-aircraft', bookInAircraftLookup);

    const bookInArrivalAirportLookup = createLookup(
        'book_in_from',
        'book-in-arrival-airport-lookup-results',
        null,
        { isAirport: true, minLength: 2 }
    );
    lookupManager.register('book-in-arrival-airport', bookInArrivalAirportLookup);

    const overflightAircraftLookup = createLookup(
        'overflight_registration',
        'overflight-aircraft-lookup-results',
        null,
        { isAircraft: true, minLength: 4, debounceMs: 300 }
    );
    lookupManager.register('overflight-aircraft', overflightAircraftLookup);

    const overflightDepartureLookup = createLookup(
        'overflight_departure_airfield',
        'overflight-departure-airport-lookup-results',
        null,
        { isAirport: true, minLength: 2 }
    );
    lookupManager.register('overflight-departure', overflightDepartureLookup);

    const overflightDestinationLookup = createLookup(
        'overflight_destination_airfield',
        'overflight-destination-airport-lookup-results',
        null,
        { isAirport: true, minLength: 2 }
    );
    lookupManager.register('overflight-destination', overflightDestinationLookup);
    
    // Attach keyboard handlers to airport input fields
    setTimeout(() => {
        if (arrivalAirportLookup.attachKeyboardHandler) arrivalAirportLookup.attachKeyboardHandler();
        if (departureAirportLookup.attachKeyboardHandler) departureAirportLookup.attachKeyboardHandler();
        if (localOutToLookup.attachKeyboardHandler) localOutToLookup.attachKeyboardHandler();
        if (bookInArrivalAirportLookup.attachKeyboardHandler) bookInArrivalAirportLookup.attachKeyboardHandler();
        if (overflightDepartureLookup.attachKeyboardHandler) overflightDepartureLookup.attachKeyboardHandler();
        if (overflightDestinationLookup.attachKeyboardHandler) overflightDestinationLookup.attachKeyboardHandler();
    }, 100);
}

// Initialize on DOM ready or immediately if already loaded
if (document.readyState === 'loading') {
    document.addEventListener('DOMContentLoaded', initializeLookups);
} else {
    initializeLookups();
}

/**
 * Convenience wrapper functions for backward compatibility
 */
function handleArrivalAirportLookup(value) {
    const lookup = lookupManager.lookups['arrival-airport'];
    if (lookup) lookup.handle(value);
}

function handleDepartureAirportLookup(value) {
    const lookup = lookupManager.lookups['departure-airport'];
    if (lookup) lookup.handle(value);
}

function handleLocalOutToAirportLookup(value) {
    const lookup = lookupManager.lookups['local-out-to'];
    if (lookup) lookup.handle(value);
}

function handleAircraftLookup(value) {
    const lookup = lookupManager.lookups['aircraft'];
    if (lookup) lookup.handle(value);
}

function handleLocalAircraftLookup(value) {
    const lookup = lookupManager.lookups['local-aircraft'];
    if (lookup) lookup.handle(value);
}

function clearArrivalAirportLookup() {
    const lookup = lookupManager.lookups['arrival-airport'];
    if (lookup) lookup.clear();
}

function clearDepartureAirportLookup() {
    const lookup = lookupManager.lookups['departure-airport'];
    if (lookup) lookup.clear();
}

function clearLocalOutToAirportLookup() {
    const lookup = lookupManager.lookups['local-out-to'];
    if (lookup) lookup.clear();
}

function clearAircraftLookup() {
    const lookup = lookupManager.lookups['aircraft'];
    if (lookup) lookup.clear();
}

function clearLocalAircraftLookup() {
    const lookup = lookupManager.lookups['local-aircraft'];
    if (lookup) lookup.clear();
}

function selectArrivalAirport(icaoCode) {
    lookupManager.selectItem('arrival-airport-lookup-results', 'in_from', icaoCode);
}

function selectDepartureAirport(icaoCode) {
    lookupManager.selectItem('departure-airport-lookup-results', 'out_to', icaoCode);
}

function selectLocalOutToAirport(icaoCode) {
    lookupManager.selectItem('local-out-to-lookup-results', 'local_out_to', icaoCode);
}

function selectLocalAircraft(registration) {
    lookupManager.selectItem('local-aircraft-lookup-results', 'local_registration', registration);
}

function handleBookInAircraftLookup(value) {
    const lookup = lookupManager.lookups['book-in-aircraft'];
    if (lookup) lookup.handle(value);
}

function handleBookInArrivalAirportLookup(value) {
    const lookup = lookupManager.lookups['book-in-arrival-airport'];
    if (lookup) lookup.handle(value);
}

function clearBookInAircraftLookup() {
    const lookup = lookupManager.lookups['book-in-aircraft'];
    if (lookup) lookup.clear();
}

function clearBookInArrivalAirportLookup() {
    const lookup = lookupManager.lookups['book-in-arrival-airport'];
    if (lookup) lookup.clear();
}

function selectBookInAircraft(registration) {
    lookupManager.selectItem('book-in-aircraft-lookup-results', 'book_in_registration', registration);
}

function selectBookInArrivalAirport(icaoCode) {
    lookupManager.selectItem('book-in-arrival-airport-lookup-results', 'book_in_from', icaoCode);
}