# Gate every pull request into `main` on the checks this repository already had
# and nobody ran automatically.
#
# Phases 1 and 3 both wrote `cargo fmt`, `cargo clippy -D warnings` and a test
# suite, and both ran them BY HAND from a workstation. That is the whole gap
# this file closes: a guard nothing invokes is a guard whose state nobody knows,
# and the repository that gets released had nothing gating it at all.
#
# Adapted from RunicGateway/installer's pr-checks.yml, which is the other Rust
# crate in this project and already solved the toolchain-on-a-shared-runner
# problem. Two differences, both because of where the crate sits:
#
#   • The crate is in `sidecar/`, not at the repo root, so every cargo step runs
#     with that working directory and the cache key reads that lockfile.
#   • There is no "does a crate exist yet" detection. The installer needed it
#     because its CI landed before its code; here the code came first.
#
# Enforcement (one-time, in the Gitea UI):
#   Repository Settings → Branches → Branch Protection (rule for `main`)
#     • Enable Status Check
#     • Status check patterns:  PR Checks / *
#   Gitea only lists a context in its dropdown after it has reported once, so let
#   this run on one PR first; the glob matches without the dropdown and keeps
#   matching as jobs are added.
#
# Scope note: `edge` is gated as well as `main` though this repo has no `edge`
# branch. Multi-phase work lands there first everywhere else in this project, and
# gating only the `main` hop would run these checks for the first time at the
# cutover — the one moment a red build is most expensive to find.

name: PR Checks

on:
  pull_request:
    branches: [main, edge]

concurrency:
  group: pr-checks-${{ github.ref }}
  cancel-in-progress: true

jobs:
  rust-gates:
    runs-on: ubuntu-latest
    timeout-minutes: 30
    defaults:
      run:
        working-directory: sidecar
    steps:
      - uses: actions/checkout@v4

      # One job runs all three gates on purpose: installing the toolchain costs
      # far more than the checks do, so splitting fmt/clippy/test into parallel
      # jobs would pay that cost three times for no wall-clock win.
      - name: Install Rust toolchain (rustfmt + clippy)
        run: |
          set -euo pipefail
          SUDO=""; [ "$(id -u)" -ne 0 ] && SUDO="sudo"
          $SUDO apt-get update
          $SUDO apt-get install -y --no-install-recommends \
            build-essential curl ca-certificates git

          if ! command -v cargo >/dev/null 2>&1; then
            curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs \
              | sh -s -- -y --profile minimal --default-toolchain stable
          fi
          echo "${HOME}/.cargo/bin" >> "$GITHUB_PATH"
          export PATH="${HOME}/.cargo/bin:${PATH}"
          rustup component add rustfmt clippy
          cargo --version && cargo fmt --version && cargo clippy --version

      # Keyed on Cargo.lock: dependency builds are reused until a dep actually
      # changes. A cache miss only makes the run slower, never wrong.
      - name: Cache cargo registry and build dir
        uses: actions/cache@v4
        with:
          path: |
            ~/.cargo/registry
            ~/.cargo/git
            sidecar/target
          key: ${{ runner.os }}-cargo-${{ hashFiles('sidecar/Cargo.lock') }}
          restore-keys: |
            ${{ runner.os }}-cargo-

      # Cheapest gate first — parses only, no compile, so a formatting slip fails
      # in seconds instead of after a full build.
      - name: cargo fmt --check
        run: cargo fmt --check

      # --all-targets covers the tests too, which is where most of this crate's
      # interesting code is. -D warnings makes a lint a failure, so the crate
      # starts clean at this bar and anything new is a regression from the PR.
      - name: cargo clippy
        run: cargo clippy --locked --all-targets -- -D warnings

      # --locked also proves Cargo.lock is in sync with Cargo.toml rather than
      # letting the build silently update it.
      - name: cargo test
        run: cargo test --locked