# Gate every pull request into `main` on the same Rust checks the release runs,
# so a formatting slip, a lint regression, or a failing test can't reach the
# deployable branch.
#
# Mirrors RunicGateway/link's pr-checks.yml — same gates in the same order as
# release.yml, so a green PR means the release will get past its own gates too.
# The one structural difference is the crate guard below.
#
# ── Crate guard ──────────────────────────────────────────────────────────────
# This repo is in the planning phase and has no Cargo project yet (the design of
# record is docs/installer/PLAN.md; Phase 1 is what creates the crate). Rather
# than leave the repo ungated until then — or land a workflow that red-Xes every
# governance/docs PR — the gates are conditional on a root Cargo.toml existing.
# Before the crate lands, the job reports green with a notice. The moment
# Phase 1 adds Cargo.toml the gates arm themselves; nothing here has to change.
#
# The crate is expected at the REPO ROOT (not a subdirectory like link/sidecar):
# this repo's sole product is the one installer binary, so there is nothing to
# namespace it against.
#
# Enforcement (one-time, in the Gitea UI):
#   Repository Settings → Branches → Branch Protection (rule for `main`)
#     • Enable Status Check
#     • Status check patterns:  PR Checks / *
#   Note: Gitea only lists a context in its dropdown after it has reported once,
#   so let this workflow run on one PR first. The `PR Checks / *` glob matches
#   without needing the dropdown.
#
# Runner: the same self-hosted `ubuntu-latest` runner release.yml uses. Rust is
# not assumed to be preinstalled, so the toolchain step bootstraps it the same
# way release.yml does (minus the MinGW cross-compile deps — PRs build for the
# host only; the Windows cross-build stays a release-time concern).

name: PR Checks

on:
  pull_request:
    branches: [main]

# A newer push to the same PR cancels the in-flight run.
concurrency:
  group: pr-checks-${{ github.ref }}
  cancel-in-progress: true

jobs:
  rust-gates:
    runs-on: ubuntu-latest
    timeout-minutes: 30
    steps:
      - uses: actions/checkout@v4

      - name: Detect whether a crate exists yet
        id: detect
        run: |
          set -euo pipefail
          if [ -f Cargo.toml ]; then
            echo "crate=true" >> "$GITHUB_OUTPUT"
            echo "==> Cargo.toml found — running the full gate set."
          else
            echo "crate=false" >> "$GITHUB_OUTPUT"
            echo "==> No Cargo.toml at the repo root yet (planning phase)."
            echo "    Skipping fmt/clippy/test. These gates arm themselves as"
            echo "    soon as Phase 1 lands the crate — see docs/installer/PLAN.md."
          fi

      # One job runs all three gates on purpose: installing the toolchain costs
      # far more than the checks themselves, 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)
        if: ${{ steps.detect.outputs.crate == 'true' }}
        run: |
          set -euo pipefail
          SUDO=""; [ "$(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
        if: ${{ steps.detect.outputs.crate == 'true' }}
        uses: actions/cache@v4
        with:
          path: |
            ~/.cargo/registry
            ~/.cargo/git
            target
          key: ${{ runner.os }}-cargo-${{ hashFiles('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
        if: ${{ steps.detect.outputs.crate == 'true' }}
        run: cargo fmt --check

      # --all-targets covers tests and examples, not just the binary.
      # -D warnings makes a lint a failure, so the crate starts clean at this bar
      # and anything new is a regression introduced by the PR.
      - name: cargo clippy
        if: ${{ steps.detect.outputs.crate == 'true' }}
        run: cargo clippy --locked --all-targets -- -D warnings

      # --locked matches release.yml: it also proves Cargo.lock is in sync with
      # Cargo.toml, rather than letting the build silently update it.
      - name: cargo test
        if: ${{ steps.detect.outputs.crate == 'true' }}
        run: cargo test --locked