#moonrockz/wit

#Scenario recipes

import {
  "moonrockz/wit/parser",
  "moonrockz/wit/scanner",
  "moonrockz/wit/span",
  "moonrockz/wit/diagnostic",
  "moonrockz/wit/ast",
  "moonrockz/wit/cst",
  "moonrockz/wit/traversal",
  "moonrockz/wit/printer",
  "moonrockz/wit/formatter",
  "moonrockz/wit/verifier",
} for "test"

#Distinguish syntax, structure and resolved semantics

test "Guide: Syntax validity does not resolve WIT names" {
  let source = "package example:app; interface api { type broken = missing; }"
  let parsed = @parser.parse(source)
  assert_true(parsed.is_valid())
  assert_true(parsed.ast.validate() && parsed.cst.validate())
  assert_true(@verifier.verify(parsed, source~) is Err(_))
}

#Parse a service interface

test "Guide: Parse a WIT document" {
  let source = "package example:greeter; interface greeter { hello: func(name: string) -> string; }"
  let scanned = @scanner.scan(source)
  assert_true(scanned.diagnostics.is_empty())
  let parsed = @parser.parse(source)
  assert_true(parsed.is_valid())
  let syntax : @ast.Tree = parsed.ast
  let concrete : @cst.Tree = parsed.cst
  assert_true(syntax.validate() && concrete.validate())
  assert_eq(concrete.to_source(), source)
  let canonical = @printer.print(syntax).unwrap()
  assert_true(syntax.equivalent(@parser.parse(canonical).ast))
}

#Inspect a resource-based API and its world

test "Guide: Inspect a resource-based API and its world" {
  let source =
    #|package example:files;
    #|interface files {
    #|  record metadata { size: u64 }
    #|  resource file {
    #|    constructor(path: string);
    #|    stat: func() -> metadata;
    #|  }
    #|  open: func(path: string) -> result<own<file>, string>;
    #|}
    #|world app { export files; }
  let parsed = @parser.parse(source)
  assert_true(parsed.is_valid())
  assert_eq(parsed.cst.to_source(), source)
  let resources = parsed.ast.nodes.filter(node => node.data.kind() == Resource)
  assert_eq(resources.length(), 1)
  guard resources[0].data is Resource(name~, methods~, has_body~, ..) else {
    fail("expected typed resource data")
  }
  assert_eq(name, "file")
  assert_true(has_body)
  assert_eq(methods.length(), 2)
  assert_true(parsed.ast.nodes.any(node => node.data.kind() == World))
  assert_true(parsed.ast.nodes.any(node => node.data.kind() == Record))
}

#Report diagnostics while the user is typing

test "Guide: Render diagnostics as editor line and column values" {
  let source = "interface broken { type missing = ; }"
  let parsed = @parser.parse(source)
  let index = @span.Source::new(source)
  let errors : ReadOnlyArray[@diagnostic.Diagnostic] = parsed.diagnostics
  assert_false(errors.is_empty())
  let locations = errors.map(diagnostic => {
    let position = index.position(diagnostic.primary.span.start).unwrap()
    "example.wit:\{position.line + 1}:\{position.column + 1}: " + diagnostic.code
  })
  assert_true(locations[0].has_prefix("example.wit:1:"))
  assert_false(parsed.is_valid())
  assert_eq(parsed.cst.to_source(), source)
}

#Read named fields for an API index

test "Guide: Index WIT declarations" {
  let parsed = @parser.parse("interface api { read: func() -> u8; write: func(value: u8); }")
  let names = []
  let report = @traversal.walk(Ast(parsed.ast), event => {
    if event.phase == Enter && event.view.kind == Function {
      if parsed.ast.nodes[event.view.index].data is Function(name~, ..) {
        names.push(name)
      }
      // Names are enough for this index; skip signature descendants.
      Prune
    } else { Continue }
  }).unwrap()
  assert_eq(names, ["read", "write"])
  assert_false(report.stopped)
}

#Refactor a type and print a new document

test "Guide: Change a type without mutating the parsed tree" {
  let parsed = @parser.parse("interface api { type byte = u8; }")
  let changed = @traversal.rewrite(parsed.ast, (_view, node) => {
    match node.data {
      PrimitiveType(name="u8") => Replace(PrimitiveType(name="u64"))
      _ => Keep
    }
  }).unwrap()
  assert_true(changed.tree.validate())
  assert_true(parsed.ast.nodes.any(node => node.data == PrimitiveType(name="u8")))
  assert_false(changed.tree.nodes.any(node => node.data == PrimitiveType(name="u8")))
  assert_true(changed.tree.nodes.any(node => node.data == PrimitiveType(name="u64")))
  let printed = @printer.print(changed.tree).unwrap()
  assert_true(printed.contains("type byte = u64;"))
  assert_true(changed.tree.equivalent(@parser.parse(printed).ast))
}

#Edit one token and retain comments

test "Guide: Edit a token and format the result" {
  let source = "// keep this comment\ninterface api { type byte = u8; }"
  let parsed = @parser.parse(source)
  let token = parsed.cst.tokens.iter().find_first(token => token.text == "u8").unwrap()
  let changed = @traversal.rewrite_cst(parsed.cst, [{ span: token.span, text: "u64" }]).unwrap()
  assert_true(changed.is_valid())
  assert_eq(changed.cst.to_source(), source.replace(old="u8", new="u64"))
  assert_eq(parsed.cst.to_source(), source)
  let formatted = @formatter.format_cst(changed.cst).unwrap()
  assert_true(formatted.has_prefix("// keep this comment\n"))
  assert_eq(@formatter.format(formatted), Ok(formatted))
}

#Select a grammar profile

test "Guide: Enable only the grammar extension your source needs" {
  let source = "interface api { type bytes = list<u8, 16>; }"
  assert_false(@parser.parse(source).is_valid())
  let features = { ..@parser.Features::default(), fixed_lists: true }
  let parsed = @parser.parse(source, features~)
  assert_true(parsed.is_valid())
  assert_eq(parsed.cst.to_source(), source)
  let formatted = @formatter.format_cst(parsed.cst, features~).unwrap()
  assert_true(@parser.parse(formatted, features~).is_valid())
}

#Handle output errors without changing user input

test "Guide: Keep invalid input unchanged and report formatting errors" {
  let source = "interface broken { type missing = ; } interface later {}"
  match @formatter.format(source) {
    Err(InvalidSyntax(diagnostics)) => assert_false(diagnostics.is_empty())
    _ => fail("expected syntax diagnostics")
  }
  assert_eq(@parser.parse(source).cst.to_source(), source)
  assert_eq(@formatter.format(source, indent_width=-1), Err(InvalidOptions))
}

#More recipes by task

#Scope

#Packages

#Validation