multi event chain

// Test 829: Multi-event chain (realistic composition)
//
// Real programs chain multiple events together with deep nesting.
// This tests that the compiler can handle:
// - 5+ events in a chain
// - 3+ levels of nested continuations
// - Data flowing through multiple stages
// - Error handling at multiple levels

const std = @import("std");

// Stage 1: Parse input
~event parse { input: []const u8 }
| parsed { value: i32 }
| invalid { msg: []const u8 }

~proc parse {
    const value = std.fmt.parseInt(i32, input, 10) catch {
        return .{ .@"invalid" = .{ .msg = "Not a number" } };
    };
    return .{ .@"parsed" = .{ .value = value } };
}

// Stage 2: Validate
~event validate { value: i32 }
| valid { value: i32 }
| invalid { msg: []const u8 }

~proc validate {
    if (value < 0 or value > 100) {
        return .{ .@"invalid" = .{ .msg = "Out of range" } };
    }
    return .{ .@"valid" = .{ .value = value } };
}

// Stage 3: Transform
~event transform { value: i32 }
| transformed { result: i32 }

~proc transform {
    return .{ .@"transformed" = .{ .result = value * 2 } };
}

// Stage 4: Format
~event format { value: i32 }
| formatted { text: []const u8 }

~proc format {
    const allocator = std.heap.page_allocator;
    const text = std.fmt.allocPrint(allocator, "Result: {}", .{value}) catch {
        return .{ .@"formatted" = .{ .text = "Error formatting" } };
    };
    return .{ .@"formatted" = .{ .text = text } };
}

// Stage 5: Display
~event display { text: []const u8 }
| done {}

~proc display {
    std.debug.print("{s}\n", .{text});
    return .{ .@"done" = .{} };
}

// The chain: parse -> validate -> transform -> format -> display
// With error handling at each stage
~parse(input: "42")
| parsed p |> validate(value: p.value)
    | valid v |> transform(value: v.value)
        | transformed t |> format(value: t.result)
            | formatted f |> display(text: f.text)
                | done |> _
    | invalid i |> display(text: i.msg)
        | done |> _
| invalid i |> display(text: i.msg)
    | done |> _