extends: script
message: "Requirement statement does not match an accepted EARS pattern."
level: error
scope: raw
script: |
  text := import("text")
  matches := []
  lines := text.split(scope, "\n")
  expect_requirement := false
  offset := 0

  for line in lines {
    trimmed := text.trim_space(line)

    if text.re_match("^###[[:space:]]+Requirement:[[:space:]]+.+$", trimmed) {
      expect_requirement = true
    } else if expect_requirement && trimmed != "" {
      normalized := text.to_lower(trimmed)
      normalized = text.re_replace("[[:space:]]+", normalized, " ")
      normalized = text.re_replace("[.!?]+$", normalized, "")

      valid := false

      // Ubiquitous: The <system> shall <response>
      if text.re_match("^the .+ shall .+$", normalized) {
        valid = true
      }

      // State-driven: While <state>, the <system> shall <response>
      if text.re_match("^while .+, the .+ shall .+$", normalized) {
        valid = true
      }

      // Event-driven: When <trigger>, the <system> shall <response>
      if text.re_match("^when .+, the .+ shall .+$", normalized) {
        valid = true
      }

      // Optional feature: Where <feature>, the <system> shall <response>
      if text.re_match("^where .+, the .+ shall .+$", normalized) {
        valid = true
      }

      // Unwanted behaviour: If <trigger>, then the <system> shall <response>
      if text.re_match("^if .+, then the .+ shall .+$", normalized) {
        valid = true
      }

      // Complex: While <state>, when <trigger>, the <system> shall <response>
      if text.re_match("^while .+, when .+, the .+ shall .+$", normalized) {
        valid = true
      }

      if !valid {
        local := text.index(line, trimmed)
        if local < 0 {
          local = 0
        }
        matches = append(matches, {begin: offset + local, end: offset + local + len(trimmed)})
      }

      expect_requirement = false
    }

    offset += len(line) + 1
  }