const std = @import("std");
const Allocator = std.mem.Allocator;

/// Remove SDL_ prefix from a name
pub fn stripSDLPrefix(name: []const u8) []const u8 {
    if (std.mem.startsWith(u8, name, "SDL_")) {
        return name[4..];
    }
    return name;
}

/// Convert SDL type name to Zig type name
/// SDL_GPUDevice -> GPUDevice
pub fn typeNameToZig(c_name: []const u8) []const u8 {
    return stripSDLPrefix(c_name);
}

/// Convert SDL function name to Zig function name
/// SDL_CreateGPUDevice -> createGPUDevice
pub fn functionNameToZig(c_name: []const u8, allocator: Allocator) ![]const u8 {
    const without_prefix = stripSDLPrefix(c_name);
    if (without_prefix.len == 0) return try allocator.dupe(u8, c_name);

    // Lowercase the first character
    var result = try allocator.dupe(u8, without_prefix);
    if (result.len > 0) {
        result[0] = std.ascii.toLower(result[0]);
    }
    return result;
}

/// Detect common prefix in a list of names
/// Returns the longest common prefix
pub fn detectCommonPrefix(names: []const []const u8, allocator: Allocator) ![]const u8 {
    if (names.len == 0) return try allocator.dupe(u8, "");
    if (names.len == 1) return try allocator.dupe(u8, names[0]);

    const first = names[0];
    var prefix_len: usize = 0;

    // Find longest common prefix
    outer: for (first, 0..) |c, i| {
        for (names[1..]) |name| {
            if (i >= name.len or name[i] != c) {
                break :outer;
            }
        }
        prefix_len = i + 1;
    }

    return try allocator.dupe(u8, first[0..prefix_len]);
}

/// Convert enum value name to Zig
/// SDL_GPU_PRIMITIVETYPE_TRIANGLELIST -> primitivetypeTrianglelist
pub fn enumValueToZig(c_name: []const u8, prefix: []const u8, allocator: Allocator) ![]const u8 {
    // Remove prefix
    var name = c_name;
    if (std.mem.startsWith(u8, name, prefix)) {
        name = name[prefix.len..];
    }

    // Convert SCREAMING_SNAKE_CASE to camelCase
    return try screaminToLowerCamel(name, allocator);
}

/// Convert flag name to Zig
/// SDL_GPU_TEXTUREUSAGE_SAMPLER -> textureusageSampler
pub fn flagNameToZig(c_name: []const u8, prefix: []const u8, allocator: Allocator) ![]const u8 {
    return enumValueToZig(c_name, prefix, allocator);
}

/// Convert SCREAMING_SNAKE_CASE to lowerCamelCase
fn screaminToLowerCamel(s: []const u8, allocator: Allocator) ![]const u8 {
    if (s.len == 0) return try allocator.dupe(u8, "");

    var result = try std.ArrayList(u8).initCapacity(allocator, s.len);
    errdefer result.deinit(allocator);

    var capitalize_next = false;
    var is_first = true;

    for (s) |c| {
        if (c == '_') {
            capitalize_next = true;
            continue;
        }

        if (is_first) {
            try result.append(allocator, std.ascii.toLower(c));
            is_first = false;
        } else if (capitalize_next) {
            try result.append(allocator, std.ascii.toUpper(c));
            capitalize_next = false;
        } else {
            try result.append(allocator, std.ascii.toLower(c));
        }
    }

    return try result.toOwnedSlice(allocator);
}

test "strip SDL prefix" {
    try std.testing.expectEqualStrings("GPUDevice", stripSDLPrefix("SDL_GPUDevice"));
    try std.testing.expectEqualStrings("Foo", stripSDLPrefix("SDL_Foo"));
    try std.testing.expectEqualStrings("Bar", stripSDLPrefix("Bar"));
}

test "type name to Zig" {
    try std.testing.expectEqualStrings("GPUDevice", typeNameToZig("SDL_GPUDevice"));
    try std.testing.expectEqualStrings("GPUPrimitiveType", typeNameToZig("SDL_GPUPrimitiveType"));
}

test "function name to Zig" {
    const name1 = try functionNameToZig("SDL_CreateGPUDevice", std.testing.allocator);
    defer std.testing.allocator.free(name1);
    try std.testing.expectEqualStrings("createGPUDevice", name1);

    const name2 = try functionNameToZig("SDL_DestroyGPUDevice", std.testing.allocator);
    defer std.testing.allocator.free(name2);
    try std.testing.expectEqualStrings("destroyGPUDevice", name2);
}

test "detect common prefix" {
    const names = [_][]const u8{
        "SDL_GPU_PRIMITIVETYPE_TRIANGLELIST",
        "SDL_GPU_PRIMITIVETYPE_TRIANGLESTRIP",
        "SDL_GPU_PRIMITIVETYPE_LINELIST",
    };

    const prefix = try detectCommonPrefix(&names, std.testing.allocator);
    defer std.testing.allocator.free(prefix);
    try std.testing.expectEqualStrings("SDL_GPU_PRIMITIVETYPE_", prefix);
}

test "enum value to Zig" {
    const result = try enumValueToZig(
        "SDL_GPU_PRIMITIVETYPE_TRIANGLELIST",
        "SDL_GPU_PRIMITIVETYPE_",
        std.testing.allocator,
    );
    defer std.testing.allocator.free(result);
    try std.testing.expectEqualStrings("trianglelist", result);
}

test "screaming to lower camel" {
    const result1 = try screaminToLowerCamel("TRIANGLE_LIST", std.testing.allocator);
    defer std.testing.allocator.free(result1);
    try std.testing.expectEqualStrings("triangleList", result1);

    const result2 = try screaminToLowerCamel("SAMPLER", std.testing.allocator);
    defer std.testing.allocator.free(result2);
    try std.testing.expectEqualStrings("sampler", result2);
}