010 shape contract

// Test: Shape contract validation for interpreted code
// Interpreted code can optionally be validated against an event signature
// This ensures responses conform to a known shape

~import "$std/runtime"
~import "$std/io"

const std = @import("std");

// =============================================================================
// The Handler Contract
// =============================================================================
// This defines what shape interpreted "handlers" must return.
// Think of it as a response schema for code sent over the wire.

~pub event handler { req: []const u8 }
| ok { status: i32, body: []const u8 }
| not_found {}
| error { message: []const u8 }

// =============================================================================
// Backend events the handler can call
// =============================================================================

~pub event db.user.get { id: i32 }
| found { name: []const u8 }
| unknown {}

~proc db.user.get {
    if (id == 1) {
        return .{ .found = .{ .name = "Alice" } };
    }
    return .{ .unknown = .{} };
}

// Register events with costs
~std.runtime:register(scope: "api") {
    handler(0)      // handler itself has no cost (it's the shape)
    db.user.get(5)  // database lookup costs 5 tokens
}

// =============================================================================
// TEST 1: Valid handler - should pass shape validation
// =============================================================================

const VALID_HANDLER =
\\~db.user.get(id: 1)
\\| found u |> ok { status: 200, body: u.name }
\\| unknown |> not_found {}
;

~std.runtime:run(source: VALID_HANDLER, scope: "api", budget: 100, shape: "handler")
| result _ |> std.io:println(text: "TEST 1 PASS: valid handler accepted")
| shape_error e |> std.io:print.ln("TEST 1 FAIL: unexpected shape error: {{ e.branch:s }}")
| exhausted _ |> std.io:println(text: "TEST 1 FAIL: exhausted")
| parse_error _ |> std.io:println(text: "TEST 1 FAIL: parse error")
| validation_error _ |> std.io:println(text: "TEST 1 FAIL: validation error")
| event_denied _ |> std.io:println(text: "TEST 1 FAIL: event denied")
| dispatch_error _ |> std.io:println(text: "TEST 1 FAIL: dispatch error")
| scope_not_found _ |> std.io:println(text: "TEST 1 FAIL: scope not found")

// =============================================================================
// TEST 2: Invalid branch name - should fail shape validation
// =============================================================================

const TYPO_HANDLER =
\\~db.user.get(id: 999)
\\| found u |> ok { status: 200, body: u.name }
\\| unknown |> not_foundy {}
;
// Note: "not_foundy" is a typo - should be "not_found"
// Using id: 999 which returns 'unknown' so the typo branch is executed

~std.runtime:run(source: TYPO_HANDLER, scope: "api", budget: 100, shape: "handler")
| result _ |> std.io:println(text: "TEST 2 FAIL: should have caught typo")
| shape_error e |> std.io:print.ln("TEST 2 PASS: caught invalid branch '{{ e.branch:s }}'")
| exhausted _ |> std.io:println(text: "TEST 2 FAIL: exhausted")
| parse_error _ |> std.io:println(text: "TEST 2 FAIL: parse error")
| validation_error _ |> std.io:println(text: "TEST 2 FAIL: validation error")
| event_denied _ |> std.io:println(text: "TEST 2 FAIL: event denied")
| dispatch_error _ |> std.io:println(text: "TEST 2 FAIL: dispatch error")
| scope_not_found _ |> std.io:println(text: "TEST 2 FAIL: scope not found")

// =============================================================================
// TEST 3: Missing required field - should fail shape validation
// =============================================================================

const MISSING_FIELD_HANDLER =
\\~db.user.get(id: 1)
\\| found u |> ok { status: 200 }
\\| unknown |> not_found {}
;
// Note: ok branch is missing required 'body' field

~std.runtime:run(source: MISSING_FIELD_HANDLER, scope: "api", budget: 100, shape: "handler")
| result _ |> std.io:println(text: "TEST 3 FAIL: should have caught missing field")
| shape_error e |> std.io:print.ln("TEST 3 PASS: caught missing field in '{{ e.branch:s }}'")
| exhausted _ |> std.io:println(text: "TEST 3 FAIL: exhausted")
| parse_error _ |> std.io:println(text: "TEST 3 FAIL: parse error")
| validation_error _ |> std.io:println(text: "TEST 3 FAIL: validation error")
| event_denied _ |> std.io:println(text: "TEST 3 FAIL: event denied")
| dispatch_error _ |> std.io:println(text: "TEST 3 FAIL: dispatch error")
| scope_not_found _ |> std.io:println(text: "TEST 3 FAIL: scope not found")

// =============================================================================
// TEST 4: Free-running mode (no shape) - typo allowed
// =============================================================================

~std.runtime:run(source: TYPO_HANDLER, scope: "api", budget: 100)
| result r |> std.io:print.ln("TEST 4 PASS: free-running mode allows any shape, got branch '{{ r.value.branch:s }}'")
| exhausted _ |> std.io:println(text: "TEST 4 FAIL: exhausted")
| parse_error _ |> std.io:println(text: "TEST 4 FAIL: parse error")
| validation_error _ |> std.io:println(text: "TEST 4 FAIL: validation error")
| shape_error _ |> std.io:println(text: "TEST 4 FAIL: shape error")
| event_denied _ |> std.io:println(text: "TEST 4 FAIL: event denied")
| dispatch_error _ |> std.io:println(text: "TEST 4 FAIL: dispatch error")
| scope_not_found _ |> std.io:println(text: "TEST 4 FAIL: scope not found")