name: Update flake hashes

on:
  workflow_dispatch:
  pull_request:
    paths:
      - "Cargo.lock"
      - "Cargo.toml"
      - "rust-toolchain.toml"

jobs:
  update-flake-hashes:
    runs-on: ubuntu-latest
    steps:
      - uses: https://code.forgejo.org/actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
        with:
          fetch-depth: 1
          fetch-tags: false
          fetch-single-branch: true
          submodules: false
          persist-credentials: false

      - uses: https://github.com/cachix/install-nix-action@56a7bb7b56d9a92d4fd1bc05758de7eea4a370a8 # v31.1.6
        with:
          nix_path: nixpkgs=channel:nixos-unstable

        # We can skip getting a toolchain hash if this was ran as a dispatch with the intent
        # to update just the rocksdb hash. If this was ran as a dispatch and the toolchain
        # files are changed, we still update them, as well as the rocksdb import.
      - name: Detect changed files
        id: changes
        run: |
          git fetch origin ${{ forgejo.base_ref }} --depth=1 || true
          if [ -n "${{ forgejo.event.pull_request.base.sha }}" ]; then
            base=${{ forgejo.event.pull_request.base.sha }}
          else
            base=$(git rev-parse HEAD~1)
          fi
          echo "Base: $base"
          echo "HEAD: $(git rev-parse HEAD)"
          git diff --name-only $base HEAD > changed_files.txt
          echo "files=$(cat changed_files.txt)" >> $FORGEJO_OUTPUT

      - name: Get new toolchain hash
        if: contains(steps.changes.outputs.files, 'Cargo.toml') || contains(steps.changes.outputs.files, 'Cargo.lock') || contains(steps.changes.outputs.files, 'rust-toolchain.toml')
        run: |
          # Set the current sha256 to an empty hash to make `nix build` calculate a new one
          awk '/fromToolchainFile *\{/{found=1; print; next} found && /sha256 =/{sub(/sha256 = .*/, "sha256 = pkgsHost.lib.fakeSha256;"); found=0} 1' flake.nix > temp.nix && mv temp.nix flake.nix

          # Build continuwuity and filter for the new hash
          # We do `|| true` because we want this to fail without stopping the workflow
          nix build .#default 2>&1 | tee >(grep 'got:' | awk '{print $2}' > new_toolchain_hash.txt) || true

          # Place the new hash in place of the empty hash
          new_hash=$(cat new_toolchain_hash.txt)
          sed -i "s|pkgsHost.lib.fakeSha256|\"$new_hash\"|" flake.nix

          echo "New hash:"
          awk -F'"' '/fromToolchainFile/{found=1; next} found && /sha256 =/{print $2; found=0}' flake.nix
          echo "Expected new hash:"
          cat new_toolchain_hash.txt

          rm new_toolchain_hash.txt

      - name: Get new rocksdb hash
        run: |
          # Set the current sha256 to an empty hash to make `nix build` calculate a new one
          awk '/repo = "rocksdb";/{found=1; print; next} found && /sha256 =/{sub(/sha256 = .*/, "sha256 = pkgsHost.lib.fakeSha256;"); found=0} 1' flake.nix > temp.nix && mv temp.nix flake.nix

          # Build continuwuity and filter for the new hash
          # We do `|| true` because we want this to fail without stopping the workflow
          nix build .#default 2>&1 | tee >(grep 'got:' | awk '{print $2}' > new_rocksdb_hash.txt) || true

          # Place the new hash in place of the empty hash
          new_hash=$(cat new_rocksdb_hash.txt)
          sed -i "s|pkgsHost.lib.fakeSha256|\"$new_hash\"|" flake.nix

          echo "New hash:"
          awk -F'"' '/repo = "rocksdb";/{found=1; next} found && /sha256 =/{print $2; found=0}' flake.nix
          echo "Expected new hash:"
          cat new_rocksdb_hash.txt

          rm new_rocksdb_hash.txt

      - name: Show diff
        run: git diff flake.nix

      - name: Push changes
        run: |
          set -euo pipefail

          if git diff --quiet --exit-code; then
            echo "No changes to commit."
            exit 0
          fi

          git config user.email "renovate@mail.ellis.link"
          git config user.name "renovate"

          REF="${{ forgejo.head_ref }}"

          git fetch origin "$REF"
          git checkout "$REF"

          git commit -a -m "chore(Nix): Updated flake hashes"

          git push origin HEAD:refs/heads/"$REF"