#!/usr/bin/env bash
#
# Process (API) docs after a successful build on GitHub Actions.
#
# Updated/changed documentation for "master" is pushed to gh-pages.
# In case of pull requests or other branches, it will get added to a separate branch.
# In case of a pull request, a compare view comment will be posted.
#
# NOTE: stdout/stderr might/should be discarded to not leak sensitive information.

echo "Post-processing (API) documentation."
echo "PR Number: $PR_NUMBER"
echo "GITHUB_HEAD_REF: $GITHUB_REF"

if [ -z "$APIDOC_TOKEN" ]; then
    echo "No APIDOC_TOKEN available. Skipping."
    exit
fi

# NOTE: DO NOT USE "set -x", or anything else that would reveal APIDOC_TOKEN!
# GitHub Actions does filter secrets, but extra caution won't hurt
set -e
set +x

# Display exit code in case of failure (probably due to 'set -x').
trap '[ "$?" = 0 ] || echo "EXIT CODE: $?"' EXIT

REPO_APIDOC="https://${APIDOC_TOKEN}@github.com/awesomeWM/apidoc"
REPO_DIR="$PWD"

export GIT_AUTHOR_NAME="awesome-robot on GitHub Actions"
export GIT_AUTHOR_EMAIL="awesome-robot@users.noreply.github.com"
export GIT_COMMITTER_NAME="$GIT_AUTHOR_NAME"
export GIT_COMMITTER_EMAIL="$GIT_AUTHOR_EMAIL"

git clone --depth 1 --branch gh-pages "$REPO_APIDOC" build/apidoc \
    2>&1 | sed "s/$APIDOC_TOKEN/APIDOC_TOKEN/g"
cd build/apidoc

# This will re-use already existing branches (updated PR).
if [ "$PR_NUMBER" != "" ]; then
    BRANCH="pr-$PR_NUMBER"
elif [ "$GITHUB_REF" != "" ] && [ "$GITHUB_REF" != "refs/heads/master" ]; then
    # Use merge-base of master in branch name, to keep different branches with
    # the same name apart.
    # shellcheck disable=SC2015
    BRANCH="$GITHUB_REF-$(cd "$REPO_DIR" \
        && git fetch --unshallow origin master \
        && git rev-parse --short "$(git merge-base HEAD FETCH_HEAD || true)" || true)"
else
    BRANCH="gh-pages"
fi
if [ "$BRANCH" != "gh-pages" ]; then
    git checkout -b "$BRANCH" "origin/${BRANCH}" 2> /dev/null || git checkout -b "$BRANCH"
fi

# Use a temporary branch for the two commits, which allows for a better UI.
git checkout -b merged-update

# Create the README for the Git repo (https://github.com/awesomeWM/apidoc).
cat > ../doc/README.md <<END
# Awesome API documentation

This repository contains the built API documentation for the
[awesome](https://github.com/awesomeWM/awesome) window manager. It is
automatically updated via GitHub Actions when the master branch changes. Hence:

## Do NOT send pull requests here

Instead, please update the source code of
[awesome](https://github.com/awesomeWM/awesome) instead.
END

# Create a patch without irrelevant changes (version / timestamp).
diff -Nur . ../doc -I "Last updated" -I "<strong>Release</strong>:" \
    -I "<h2>API documentation for awesome, a highly configurable X window manager (version .*)\.</h2>" \
    -x .git | patch -p1

git add --all .
if git diff --cached --exit-code --quiet; then
    echo "Documentation has not changed."
    exit
fi

LAST_COMMIT_MSG="$(cd "$REPO_DIR" && git log -1 --pretty=format:%s)"
LAST_COMMIT="$(cd "$REPO_DIR" && git rev-parse --short HEAD)"

# Commit the relevant changes.
COMMIT_MSG="Update docs for $AWESOME_VERSION via Github Actions

Last commit message:
$LAST_COMMIT_MSG

Commits: $GITHUB_COMPARE
Build URL: $GITHUB_SERVER_URL/$GITHUB_REPOSITORY/actions/runs/$GITHUB_RUN_ID"

git commit -m "[relevant] $COMMIT_MSG"

# Commit the irrelevant changes.
mv .git ../doc
cd ../doc
git add --all .
if git commit -m "[boilerplate] $COMMIT_MSG"; then
    # Reorder/swap commits, to have "relevant" after "boilerplate".
    # This makes it show up earlier in the Github interface etc.
    git tag _old
    git reset --hard HEAD~2
    git cherry-pick _old _old~1
    RELEVANT_REV="$(git rev-parse --short HEAD)"
    git tag -d _old
fi

git checkout "$BRANCH"
OLD_REV="$(git rev-parse --short HEAD)"
if [ "$PR_NUMBER" != "" ]; then
    MERGE_COMMIT_MSG="$COMMIT_MSG
Pull request: https://github.com/awesomeWM/awesome/pull/${PR_NUMBER}"
else
    PR_OR_ISSUE="$(echo "$COMMIT_MSG" | head -n 1 | grep -o '#[0-9]\+' || true)"
    if [ -n "$PR_OR_ISSUE" ]; then
        MERGE_COMMIT_MSG="$COMMIT_MSG
Ref: https://github.com/awesomeWM/awesome/pull/${PR_OR_ISSUE}"
    else
        PR_OR_ISSUE_URL="$(echo "$COMMIT_MSG" \
            | grep -Eo 'https://github.com/awesomeWM/awesome/(issues|pull)/[0-9]+' || true)"
        if [ -n "$PR_OR_ISSUE_URL" ]; then
            MERGE_COMMIT_MSG="$COMMIT_MSG
Ref: $PR_OR_ISSUE_URL"
        else
            MERGE_COMMIT_MSG="$COMMIT_MSG
Commit: https://github.com/awesomeWM/awesome/commit/${LAST_COMMIT}
Tree:   https://github.com/awesomeWM/awesome/commits/${LAST_COMMIT}"
        fi
    fi
fi
git merge --no-ff -m "$MERGE_COMMIT_MSG" merged-update
NEW_REV="$(git rev-parse --short HEAD)"

git push origin "$BRANCH" 2>&1 | sed "s/$APIDOC_TOKEN/APIDOC_TOKEN/g"

# Generate compare view links.
# NOTE: use "\n" for line endings, not real ones for valid json!
COMPARE_LINKS="Compare view: https://github.com/awesomeWM/apidoc/compare/${OLD_REV}...${NEW_REV}"
COMPARE_LINKS="$COMPARE_LINKS\nRelevant changes: https://github.com/awesomeWM/apidoc/commit/${RELEVANT_REV}"
if [ "$BRANCH" != "gh-pages" ]; then
    COMPARE_LINKS="$COMPARE_LINKS\nComparison against master (gh-pages): https://github.com/awesomeWM/apidoc/compare/gh-pages...${NEW_REV}"
fi
# shellcheck disable=SC2028
printf %s "Compare links:\n$COMPARE_LINKS"

# Post a comment to the PR.
if [ "$PR_NUMBER" != "" ]; then
    curl -H "Authorization: token $APIDOC_TOKEN" \
        -d "{\"body\": \"Documentation has been updated for this PR.\n\n$COMPARE_LINKS\"}" \
        "https://api.github.com/repos/awesomeWM/awesome/issues/${PR_NUMBER}/comments" \
        2>&1 | sed "s/$APIDOC_TOKEN/APIDOC_TOKEN/g"
fi

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