#!/usr/bin/env bash
# SPDX-License-Identifier: Apache-2.0
# Copyright (C) 2021 Arm Limited or its affiliates and Contributors. All rights reserved.

[[ "$TRACE" ]] && set -x
set -euo pipefail

### Example:
### Building a series of commits in distinct worktrees under d-aarch64/
###
### export CCACHE_DIR="$(git rev-parse --show-toplevel)/ccache" CCACHE_MAXSIZE=50G
### git-list-between 03/01/2021 04/01/2021 llvm clang | awk '{print $1}' | cmake-build-commits d-aarch64 llvm clang
print_help() {
    echo 'Usage: manyclangs-build-commits [WORKTREES] [PATHSPEC]...'
    echo ''
    echo 'Builds the commits read in on the standard input in separate worktrees under WORKTREES.'
    echo 'Only the directories matched by PATHSPEC are checked out before each build.'
}

# create_build COMMIT
# Checks out COMMIT and builds it, then stores a copy in $WORKTREES/$COMMIT
create_build() {
    COMMIT="$1"
    CHECKOUT_PATHSPEC=(${@:2})
    # Checksum all CMakeLists.txt
    CMAKELISTS_SHA1_OLD="$(sha1sum <(find . -name 'CMakeLists.txt' -exec sha1sum {} +) | awk '{print $1}')"
    echo "Processing commit $COMMIT... ($(pwd))"
    git reset --soft "$COMMIT"
    # Do the checkout; --no-overlay also removes old files
    git -c core.checkStat=minimal -c advice.detachedHead=false checkout --no-overlay --progress "$COMMIT" -- "${CHECKOUT_PATHSPEC[@]}"
    # Print commit
    git show --format=fuller -s
    # Checksum again to compare
    CMAKELISTS_SHA1_NEW="$(sha1sum <(find . -name 'CMakeLists.txt' -exec sha1sum {} +) | awk '{print $1}')"
    echo "$COMMIT" > ./COMMIT
    ccache -z
    BUILD_LOGS="$(mktemp -d)"
    # Do not fail script if build fails
    set +e
    (
        # Exit subshell early
        set -e
        mkdir -p ./build
        cd ./build
        if [[ "$CMAKELISTS_SHA1_OLD" == "$CMAKELISTS_SHA1_NEW" && -d ./CMakeFiles && ! -f ./.FAILED ]]; then
            echo 'Build configuration is unchanged.'
        else
            rm -r ./.FAILED ./CMakeFiles ./CMakeCache.txt || true
            "$SOURCE_DIR"/manyclangs-cmake ../llvm
        fi

        "$SOURCE_DIR"/manyclangs-build . |& tee -a "$BUILD_LOGS/build.log"

        # Add license information
        cp ../llvm/LICENSE.TXT ./LICENSE-llvm.txt
        cp ../clang/LICENSE.TXT ./LICENSE-clang.txt
        {
            echo 'These builds were done as part of the elfshaker/manyclangs project,'
            echo 'please see https://github.com/elfshaker/manyclangs for more information'
        } > ./README
    )
    BUILD_STATUS="$?"
    set -e
    ccache -s
    # Create a copy of the current tree
    (cd "$ROOT_DIR" && "$SOURCE_DIR"/git-checkout-worktree "$WORKTREES/$BUILD_WORKTREE" "$WORKTREES/$COMMIT")
    # Clean failed builds and store logs
    if [[ "$BUILD_STATUS" != "0" ]]; then
        echo "Build of $COMMIT failed with exit code: $BUILD_STATUS!"
        cp "$ROOT_DIR/$WORKTREES/$COMMIT/build/CMakeFiles/CMake"*.log "$BUILD_LOGS"/ || true
        rm -r "$ROOT_DIR/$WORKTREES/$COMMIT/build/"*
        cp "$BUILD_LOGS"/* "$ROOT_DIR/$WORKTREES/$COMMIT/build/" || true
        # Create .FAILED to re-run cmake later
        touch "$ROOT_DIR/$WORKTREES/$BUILD_WORKTREE/build/.FAILED"
    fi
    rm -r "$BUILD_LOGS"
}

main() {
    SOURCE_DIR="$(realpath "$(dirname "${BASH_SOURCE[0]}")")"

    # The directory containing the worktrees to create
    WORKTREES="$1"
    CHECKOUT_PATHSPEC=(${@:2})
    ROOT_DIR="$(pwd)"
    # Worktree used for building. Ensures consistent paths.
    BUILD_WORKTREE="build-$(openssl rand -hex 8)"

    # Do the initial checkout
    git worktree add --no-checkout -B "$WORKTREES/$BUILD_WORKTREE" "$WORKTREES/$BUILD_WORKTREE"
    cd "$WORKTREES/$BUILD_WORKTREE"
    read -r COMMIT
    git checkout "$COMMIT" -- "${CHECKOUT_PATHSPEC[@]}"
    time create_build "$COMMIT" "${CHECKOUT_PATHSPEC[@]}"

    while read -r COMMIT; do
        time create_build "$COMMIT" "${CHECKOUT_PATHSPEC[@]}"
    done
}

case "${1:--h}" in
    -h | --help)
        print_help
        [ $# -ne 0 ]
        exit $?
        ;;
    *)
        main "$@"
        ;;
esac