const std = @import("std");

pub const Segment = union(enum) {
    literal: []const u8,
    identifier: []const u8,

    pub fn format(self: *const @This(), writer: *std.Io.Writer) !void {
        switch (self.*) {
            .literal => |l| try writer.print("{s}", .{l}),
            .identifier => |l| try writer.print("{{{s}}}", .{l}),
        }
    }
};

segments: []const Segment,

pub const index: @This() = .{ .segments = &.{} };

pub fn fromAny(comptime route: anytype) @This() {
    var segments: []const Segment = &.{};

    if (route == .index) {
        return index;
    }

    inline for (route) |r| {
        const segment: []const Segment = &.{switch (@TypeOf(r)) {
            @EnumLiteral() => .{ .identifier = @tagName(r) },
            else => .{ .literal = r },
        }};

        segments = segments ++ segment;
    }

    return .{ .segments = segments };
}

pub fn format(self: *const @This(), writer: *std.Io.Writer) !void {
    for (self.segments) |*seg| {
        try writer.print("/{f}", .{seg});
    }
}

pub fn isPrefixOf(self: *const @This(), other: *const @This()) bool {
    if (self.segments.len > other.segments.len) {
        return false;
    }

    for (self.segments, other.segments[0..self.segments.len]) |s, o| {
        if (std.meta.activeTag(s) != std.meta.activeTag(o)) {
            return false;
        }

        if (s == .literal) {
            if (!std.mem.eql(u8, s.literal, o.literal)) {
                return false;
            }
        }
    }

    return true;
}

pub fn equals(self: *const @This(), other: *const @This()) bool {
    if (self.segments.len != other.segments.len) {
        return false;
    }

    for (self.segments, other.segments) |s, o| {
        if (std.meta.activeTag(s) != std.meta.activeTag(o)) {
            return false;
        }

        if (s == .literal) {
            if (!std.mem.eql(u8, s.literal, o.literal)) {
                return false;
            }
        }
    }

    return true;
}

test "isPrefixOf" {
    {
        const parent = comptime fromAny(.{ "api", "images", .id });
        const child = comptime fromAny(.{ "api", "images", .id, "metadata" });
        try std.testing.expect(parent.isPrefixOf(&child));
    }
    {
        const parent = comptime fromAny(.{ "api", "videos", .id });
        const child = comptime fromAny(.{ "api", "images", .id, "metadata" });
        try std.testing.expect(!parent.isPrefixOf(&child));
    }
}