using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;

namespace GisConverter.Lib.Models
{
    /// <summary>
    /// Canonical set of supported target format option keys used by the library, host and tests.
    /// </summary>
    /// <remarks>
    /// <para>
    /// Purpose
    /// - Provide a single, discoverable, immutable source of truth for the friendly target option
    ///   keys used across the codebase (for example "GeoJson", "Shapefile", "Csv").
    /// - Consumers (ConverterFactory, tests, UI lists, README documentation) should reference this
    ///   collection rather than duplicating literal strings to reduce maintenance and avoid drift.
    /// </para>
    ///
    /// <para>
    /// API & usage
    /// - Use <see cref="Values"/> to enumerate the supported option keys in a stable, read-only form.
    /// - Use <see cref="Contains(string)"/> for a simple, case-insensitive membership check.
    /// - The collection is intentionally small and stable; callers should not attempt to mutate it.
    /// </para>
    ///
    /// <para>
    /// Relationship with other components
    /// - Keep this set synchronized with:
    ///   - <c>ConverterFactory</c> registrations so the factory can resolve display keys.
    ///   - <c>FileExtensionHelpers</c> and <c>ConverterUtils.ConversionOptionToDriver</c> mappings so
    ///     option keys map to expected drivers and extensions.
    ///   - Integration test helpers (for example <c>IntegrationTestConstants</c>) and TestData folders.
    /// </para>
    ///
    /// <para>
    /// Thread-safety & lifetime
    /// - The underlying collection is an immutable, read-only snapshot and therefore safe for concurrent use.
    /// - The backing field is initialized once and never modified.
    /// </para>
    ///
    /// <para>
    /// Maintenance guidance
    /// - Adding a new target option:
    ///   1. Add the friendly key to the <c>s_values</c> array below.
    ///   2. Register the converter in <c>ConverterFactory</c> (or update test injection maps).
    ///   3. Add/adjust driver and extension mappings in <c>ConverterUtils</c> and <c>FileExtensionHelpers</c>.
    ///   4. Add corresponding unit/integration tests and TestData samples.
    /// - When renaming or removing a key, update callers and tests in the same change to avoid transient breakage.
    /// </para>
    ///
    /// <para>
    /// Test guidance
    /// - Tests that iterate supported targets should consume <see cref="Values"/> rather than embedding literals.
    /// - Assertion guidance: prefer membership checks and stable token assertions; avoid asserting on exact ordering unless
    ///   ordering is a documented contract.
    /// </para>
    ///
    /// </remarks>
    public static class SupportedFormats
    {
        private static readonly IReadOnlyList<string> s_values = new ReadOnlyCollection<string>(new[]
        {
            "Csv",
            "EsriJson",
            "Gdb",
            "GeoJson",
            "GeoJsonSeq",
            "GeoPackage",
            "Gml",
            "Gpx",
            "Kml",
            "Kmz",
            "MapInfoInterchange",
            "MapInfoTab",
            "Osm",
            "Shapefile",
            "TopoJson"
        });

        /// <summary>
        /// Immutable snapshot of supported target option keys.
        /// </summary>
        public static IReadOnlyList<string> Values => s_values;

        /// <summary>
        /// Case-insensitive membership check for a candidate option key.
        /// </summary>
        /// <param name="option">Candidate option key to test.</param>
        /// <returns>True when the option is one of the supported keys; false otherwise.</returns>
        public static bool Contains(string option)
        {
            if (string.IsNullOrWhiteSpace(option)) return false;
            return s_values.Any(s => string.Equals(s, option.Trim(), StringComparison.OrdinalIgnoreCase));
        }
    }
}