#!/usr/bin/env bash
set -u

ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
# shellcheck source=test/harness.sh
source "$ROOT/test/harness.sh"
# shellcheck source=lib/changelog.sh
source "$ROOT/lib/changelog.sh"

TMP="$(mktemp -d)"
trap 'rm -rf "$TMP"' EXIT

FIXTURE="$TMP/CHANGELOG.md"
cat >"$FIXTURE" <<'EOF'
# Changelog

Preamble prose belongs to no section.

## Unreleased

- Not yet released and never part of a version.

## 0.7.0 — 2026-07-20

### Added

- The seven-oh entry.

## 0.7.0-rc1 — 2026-07-19

- The release-candidate entry.

## 0.6.0 — 2026-07-18

- The six-oh entry.

## 0.5.0 — 2026-07-15

## 0.4.0
- A date-less version heading also parses.
EOF

assert_section() {
  local version="$1" expected="$2" actual
  actual="$(changelog_section "$FIXTURE" "$version")"
  [ "$actual" = "$expected" ] || {
    printf 'wanted:\n%s\ngot:\n%s\n' "$expected" "$actual"
    return 1
  }
}

check "extracts one section body exactly" 0 "" assert_section 0.7.0 $'### Added\n\n- The seven-oh entry.'
check "adjacent older section does not bleed" 0 "" assert_section 0.6.0 '- The six-oh entry.'
check "whole match selects the rc section" 0 "" assert_section 0.7.0-rc1 '- The release-candidate entry.'
check "Unreleased parses as a date-less heading" 0 "" assert_section Unreleased '- Not yet released and never part of a version.'
check "date-less version heading parses" 0 "" assert_section 0.4.0 '- A date-less version heading also parses.'
check "empty stamped section returns empty output" 0 "" assert_section 0.5.0 ""
check "missing section returns empty output" 0 "" assert_section 9.9.9 ""

PROBLEM_FIXTURE="$TMP/CHANGELOG.problems.md"
assert_problem() {
  local version="$1" expected_status="$2" expected="$3"
  check "predicate: $version / $expected" "$expected_status" "$expected" \
    changelog_section_problem "$PROBLEM_FIXTURE" "$version"
}

cat >"$PROBLEM_FIXTURE" <<'EOF'
# Changelog

## Unreleased

### Added

### Changed

### Fixed

## 1.0.0

- Flat dash entry.

## 1.1.0

* Flat star entry.

## 1.2.0

### Fixed

- Fixed entry.

## 1.3.0

### Added

- Added entry.

### Changed

* Changed entry.

### Fixed

- Fixed entry.

## 1.4.0

## 1.5.0

### Added

## 1.6.0

### Added

### Fixed

- Fixed entry.
EOF

assert_problem Unreleased 0 ""
assert_problem 1.0.0 0 ""
assert_problem 1.1.0 0 ""
assert_problem 1.2.0 0 ""
assert_problem 1.3.0 0 ""
assert_problem 1.4.0 1 "section '1.4.0' has no entries — a heading is not an entry"
assert_problem 1.5.0 1 "section '1.5.0' has no entries — a heading is not an entry"
assert_problem 1.6.0 1 "section '1.6.0' has an empty heading: '### Added'"
assert_problem 9.9.9 1 "no section for '9.9.9'"

MISSING_UNRELEASED_FIXTURE="$TMP/CHANGELOG.missing-unreleased.md"
cat >"$MISSING_UNRELEASED_FIXTURE" <<'EOF'
# Changelog

## 1.0.0

- Released entry.
EOF
check "predicate: absent Unreleased still refuses" 1 "no section for 'Unreleased'" \
  changelog_section_problem "$MISSING_UNRELEASED_FIXTURE" Unreleased

WRAPPER="$ROOT/bin/changelog-section"
check "wrapper publishes the requested body" 0 "The seven-oh entry" "$WRAPPER" 0.7.0 "$FIXTURE"
check "wrapper refuses an empty section" 1 "no section for '0.5.0'" "$WRAPPER" 0.5.0 "$FIXTURE"
check "wrapper refuses an absent section" 1 "no section for '9.9.9'" "$WRAPPER" 9.9.9 "$FIXTURE"
check "wrapper explains how the release PR fixes refusal" 1 "stamps the Unreleased section" "$WRAPPER" 9.9.9 "$FIXTURE"
check "wrapper refuses a heading-only version section" 1 \
  "section '1.5.0' has no entries — a heading is not an entry" \
  "$WRAPPER" 1.5.0 "$PROBLEM_FIXTURE"
check "wrapper names the first dangling heading" 1 \
  "section '1.6.0' has an empty heading: '### Added'" \
  "$WRAPPER" 1.6.0 "$PROBLEM_FIXTURE"
check "wrapper prints seeded empty Unreleased without refusing" 0 "### Added" \
  "$WRAPPER" Unreleased "$PROBLEM_FIXTURE"
check "wrapper requires a version" 2 "usage:" "$WRAPPER"
check "wrapper refuses a missing file" 1 "no such file" "$WRAPPER" 1.0.0 "$TMP/missing.md"

mkdir "$TMP/default-file"
cp "$FIXTURE" "$TMP/default-file/CHANGELOG.md"
# The child shell, not this one, expands its positional parameters.
# shellcheck disable=SC2016
check "version alone reads the default changelog" 0 "The seven-oh entry" \
  bash -c 'cd "$1" && "$2" "$3"' _ "$TMP/default-file" "$WRAPPER" 0.7.0

REALISTIC="$ROOT/test/fixtures/CHANGELOG.realistic.md"
check "realistic changelog keeps its production heading shape" 0 "A mint records its provenance" \
  "$WRAPPER" 0.9.0 "$REALISTIC"
check "realistic adjacent release remains independently extractable" 0 "Merging the release PR" \
  "$WRAPPER" 0.8.0 "$REALISTIC"

summary