name: CI

on:
  push:
    branches: [main, master]
  pull_request:

env:
  CARGO_TERM_COLOR: always
  # Pin the toolchain to the declared MSRV so CI matches production.
  RUST_TOOLCHAIN: 1.90.0
  GO_VERSION: "1.25.0"

jobs:
  rust:
    name: Rust (fmt / clippy / test / build)
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Install Rust
        uses: dtolnay/rust-toolchain@stable
        with:
          toolchain: ${{ env.RUST_TOOLCHAIN }}
          components: rustfmt, clippy

      - name: Cache Cargo registry and build
        uses: actions/cache@v4
        with:
          path: |
            ~/.cargo/registry
            ~/.cargo/git
            target
          key: ${{ runner.os }}-cargo-${{ hashFiles('Cargo.lock') }}
          restore-keys: |
            ${{ runner.os }}-cargo-

      - name: Format check
        run: cargo fmt --check

      - name: Test
        run: cargo test --locked

      - name: Clippy
        run: cargo clippy --locked --all-targets -- -D warnings

      - name: Release build
        run: cargo build --locked --release

      - name: Upload release binary
        uses: actions/upload-artifact@v4
        with:
          name: balance-server-release
          path: target/release/balance-server
          if-no-files-found: error

  go:
    name: Go (test / vet / build)
    runs-on: ubuntu-latest
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Install Go
        uses: actions/setup-go@v5
        with:
          go-version: ${{ env.GO_VERSION }}

      - name: Cache Go modules
        uses: actions/cache@v4
        with:
          path: ~/go/pkg/mod
          key: ${{ runner.os }}-go-${{ hashFiles('**/go.sum') }}
          restore-keys: |
            ${{ runner.os }}-go-

      - name: Test
        run: go test ./...

      - name: Vet
        run: go vet ./...

      - name: Build
        run: go build ./...

  compatibility:
    name: Go ↔ Rust differential + SQLite takeover
    runs-on: ubuntu-latest
    needs: [rust, go]
    steps:
      - name: Checkout
        uses: actions/checkout@v4

      - name: Install Rust
        uses: dtolnay/rust-toolchain@stable
        with:
          toolchain: ${{ env.RUST_TOOLCHAIN }}

      - name: Install Go
        uses: actions/setup-go@v5
        with:
          go-version: ${{ env.GO_VERSION }}

      - name: Install Python
        uses: actions/setup-python@v5
        with:
          python-version: "3.12"

      - name: Cache Cargo registry and build
        uses: actions/cache@v4
        with:
          path: |
            ~/.cargo/registry
            ~/.cargo/git
            target
          key: ${{ runner.os }}-cargo-${{ hashFiles('Cargo.lock') }}
          restore-keys: |
            ${{ runner.os }}-cargo-

      - name: Build Rust (debug) and Go reference
        run: |
          cargo build --locked
          go build -o target/integration/go-server ./cmd/balance-server

      - name: Run differential compatibility scenarios
        run: python3 tools/compatibility.py --rust-binary target/debug/balance-server