# climaybe — AI Changelog Generator (Reusable Workflow)
# Uses Gemini when available, otherwise falls back to GitHub Models.

name: AI Changelog

on:
  workflow_call:
    inputs:
      base_ref:
        description: 'Base ref (tag or commit) to collect commits from'
        required: true
        type: string
      head_ref:
        description: 'Head ref to collect commits to (default: HEAD)'
        required: false
        type: string
        default: 'HEAD'
    outputs:
      changelog:
        description: 'Generated changelog in markdown format'
        value: ${{ jobs.generate.outputs.changelog }}
    secrets:
      GEMINI_API_KEY:
        required: false

jobs:
  generate:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      models: read
    outputs:
      changelog: ${{ steps.ai.outputs.changelog || steps.no_commits.outputs.changelog }}

    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Collect commits
        id: commits
        run: |
          COMMITS=$(git log --pretty=format:"%h %s" ${{ inputs.base_ref }}..${{ inputs.head_ref }} 2>/dev/null || echo "")
          if [ -z "$COMMITS" ]; then
            echo "No commits found between ${{ inputs.base_ref }} and ${{ inputs.head_ref }}"
            echo "has_commits=false" >> $GITHUB_OUTPUT
            exit 0
          fi
          # File avoids huge env vars and shell escaping; jq reads via --rawfile (never use --argjson for raw log text).
          printf '%s\n' "$COMMITS" > commits-for-ai.txt
          echo "has_commits=true" >> $GITHUB_OUTPUT

      - name: Generate changelog (Gemini -> GitHub Models fallback)
        id: ai
        if: steps.commits.outputs.has_commits == 'true'
        env:
          GEMINI_API_KEY: ${{ secrets.GEMINI_API_KEY }}
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          COMMITS=$(cat commits-for-ai.txt)
          PROVIDER="fallback"

          PROMPT=$(cat <<'PROMPT_EOF'
          You are a changelog generator for a Shopify theme repository.
          Given the following git commits, classify each into one of these categories:
          - **Features**: New functionality
          - **Fixes**: Bug fixes
          - **Improvements**: Enhancements to existing features
          - **Chore**: Maintenance, refactoring, docs

          Format the output as a markdown changelog. Group by category.
          Omit empty categories. Write concise, merchant-friendly descriptions.
          Do NOT include commit hashes in the output.

          Commits:
          PROMPT_EOF
          )

          CHANGELOG=""

          # 1) Gemini path (if secret exists)
          if [ -n "$GEMINI_API_KEY" ]; then
            PAYLOAD=$(jq -n \
              --arg prompt "$PROMPT" \
              --rawfile commits commits-for-ai.txt \
              '{
                "contents": [{
                  "parts": [{"text": ($prompt + "\n" + $commits)}]
                }],
                "generationConfig": {
                  "temperature": 0.3,
                  "maxOutputTokens": 2048
                }
              }')

            RESPONSE=$(curl -s -X POST \
              "https://generativelanguage.googleapis.com/v1beta/models/gemini-2.0-flash:generateContent?key=${GEMINI_API_KEY}" \
              -H "Content-Type: application/json" \
              -d "$PAYLOAD")

            CHANGELOG=$(echo "$RESPONSE" | jq -r '.candidates[0].content.parts[0].text // empty' 2>/dev/null || true)
            if [ -n "$CHANGELOG" ] && [ "$CHANGELOG" != "null" ]; then
              PROVIDER="gemini"
            fi
          fi

          # 2) GitHub Models path (Copilot-backed models)
          if [ -z "$CHANGELOG" ] || [ "$CHANGELOG" = "null" ]; then
            GH_PAYLOAD=$(jq -n \
              --arg prompt "$PROMPT" \
              --rawfile commits commits-for-ai.txt \
              '{
                "model": "gpt-4o-mini",
                "messages": [
                  {"role":"system","content":"You are a changelog generator for Shopify theme repos. Output markdown only."},
                  {"role":"user","content": ($prompt + "\n" + $commits)}
                ],
                "temperature": 0.3,
                "max_tokens": 1200
              }')

            GH_RESPONSE=$(curl -s -X POST \
              "https://models.inference.ai.azure.com/chat/completions" \
              -H "Content-Type: application/json" \
              -H "Authorization: Bearer ${GITHUB_TOKEN}" \
              -d "$GH_PAYLOAD")

            CHANGELOG=$(echo "$GH_RESPONSE" | jq -r '.choices[0].message.content // empty' 2>/dev/null || true)
            if [ -n "$CHANGELOG" ] && [ "$CHANGELOG" != "null" ]; then
              PROVIDER="github-models"
            fi
          fi

          # 3) Safe fallback if both providers fail
          if [ -z "$CHANGELOG" ] || [ "$CHANGELOG" = "null" ]; then
            COMMIT_LINES="$COMMITS"
            CHANGELOG=$(printf "## Chore\n")
            while IFS= read -r line; do
              [ -z "$line" ] && continue
              SUBJECT="${line#* }"
              CHANGELOG="${CHANGELOG}- ${SUBJECT}\n"
            done <<< "$COMMIT_LINES"
            PROVIDER="static-fallback"
          fi

          echo "Changelog provider: $PROVIDER"

          # Write to output (multiline)
          {
            echo "changelog<<CHANGELOG_EOF"
            printf "%b\n" "$CHANGELOG"
            echo "CHANGELOG_EOF"
          } >> $GITHUB_OUTPUT

      - name: Fallback if no commits
        id: no_commits
        if: steps.commits.outputs.has_commits != 'true'
        run: |
          {
            echo "changelog<<CHANGELOG_EOF"
            echo "No changes detected."
            echo "CHANGELOG_EOF"
          } >> $GITHUB_OUTPUT