name: skill-coverage
# NOTE: The issue_comment trigger sources this workflow from the default branch.
# The /skill-coverage slash command will only work after this workflow is merged to main.

on:
  pull_request:
    paths:
      - 'plugins/**'
      - 'tests/**'
  issue_comment:
    types: [created]

concurrency:
  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.event.issue.number || github.ref }}
  cancel-in-progress: true

permissions: {}

jobs:
  # ──────────────────────────────────────────────────────────────
  #  Job 1: Analyze — runs trusted script with read-only permissions
  #         Checks out base branch for tooling, PR head into a
  #         separate worktree so untrusted code is never executed.
  # ──────────────────────────────────────────────────────────────
  analyze:
    if: >-
      github.event_name == 'pull_request' ||
      (github.event_name == 'issue_comment' &&
       github.event.issue.pull_request &&
       (github.event.comment.body == '/skill-coverage' ||
        startsWith(github.event.comment.body, '/skill-coverage ') ||
        startsWith(github.event.comment.body, '/skill-coverage\n')))
    runs-on: ubuntu-latest
    permissions:
      contents: read
    outputs:
      count: ${{ steps.detect.outputs.count }}
      pr_number: ${{ github.event.pull_request.number || steps.pr-ref.outputs.pr_number }}

    steps:
      - name: Check commenter permissions
        id: check-perms
        if: github.event_name == 'issue_comment'
        uses: actions/github-script@373c709c69115d41ff229c7e5df9f8788daa9553 # v9
        with:
          script: |
            const { data: perm } = await github.rest.repos.getCollaboratorPermissionLevel({
              owner: context.repo.owner,
              repo: context.repo.repo,
              username: context.actor
            });
            const allowed = ['admin', 'write', 'maintain'];
            if (!allowed.includes(perm.permission)) {
              core.setFailed(`User ${context.actor} does not have write access (permission: ${perm.permission}).`);
            }

      - name: Parse slash command arguments
        id: parse-command
        if: github.event_name == 'issue_comment'
        shell: bash
        env:
          COMMENT_BODY: ${{ github.event.comment.body }}
        run: |
          # Extract the first line of the command
          cmd_line=$(echo "$COMMENT_BODY" | head -n 1)

          # Strip the command prefix
          args="${cmd_line#/skill-coverage}"
          args="$(echo "$args" | xargs)"  # trim whitespace

          if [ -z "$args" ]; then
            echo "mode=auto" >> "$GITHUB_OUTPUT"
            echo "plugin=" >> "$GITHUB_OUTPUT"
            echo "skill=" >> "$GITHUB_OUTPUT"
          else
            # Parse: plugin [skill]
            plugin=$(echo "$args" | awk '{print $1}')
            skill=$(echo "$args" | awk '{print $2}')
            echo "mode=explicit" >> "$GITHUB_OUTPUT"
            echo "plugin=$plugin" >> "$GITHUB_OUTPUT"
            echo "skill=$skill" >> "$GITHUB_OUTPUT"
          fi

      - name: Add reaction to comment
        if: github.event_name == 'issue_comment'
        continue-on-error: true
        uses: actions/github-script@373c709c69115d41ff229c7e5df9f8788daa9553 # v9
        with:
          script: |
            await github.rest.reactions.createForIssueComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              comment_id: context.payload.comment.id,
              content: 'eyes'
            });

      - name: Get PR ref for comment trigger
        id: pr-ref
        if: github.event_name == 'issue_comment'
        uses: actions/github-script@373c709c69115d41ff229c7e5df9f8788daa9553 # v9
        with:
          script: |
            const pr = await github.rest.pulls.get({
              owner: context.repo.owner,
              repo: context.repo.repo,
              pull_number: context.issue.number
            });
            core.setOutput('sha', pr.data.head.sha);
            core.setOutput('base_sha', pr.data.base.sha);
            core.setOutput('pr_number', context.issue.number);

      # Checkout the default branch for trusted tooling (Measure-SkillCoverage.ps1),
      # then fetch the PR head into a separate worktree so untrusted code is never executed.
      - name: Checkout base branch (trusted tooling)
        uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1 # v6
        with:
          persist-credentials: false

      - name: Fetch PR head into worktree
        shell: bash
        env:
          PR_REF: ${{ github.event_name == 'issue_comment' && format('refs/pull/{0}/head', steps.pr-ref.outputs.pr_number) || format('refs/pull/{0}/head', github.event.pull_request.number) }}
        run: |
          git fetch --depth=1 origin "$PR_REF":pr-head-ref
          git worktree add pr-head pr-head-ref

      - name: Fetch full history for diff
        run: git fetch --unshallow || true

      - name: Detect changed plugins and skills
        id: detect
        shell: pwsh
        env:
          EVENT_NAME: ${{ github.event_name }}
          CMD_MODE: ${{ steps.parse-command.outputs.mode }}
          CMD_PLUGIN: ${{ steps.parse-command.outputs.plugin }}
          CMD_SKILL: ${{ steps.parse-command.outputs.skill }}
          PR_BASE_SHA: ${{ github.event.pull_request.base.sha || steps.pr-ref.outputs.base_sha }}
          PR_HEAD_SHA: ${{ github.event.pull_request.head.sha || steps.pr-ref.outputs.sha }}
        run: |
          # If explicit plugin/skill was provided via slash command, use that directly
          if ($env:EVENT_NAME -eq 'issue_comment' -and $env:CMD_MODE -eq 'explicit') {
            $targets = @([PSCustomObject]@{ Plugin = $env:CMD_PLUGIN; Skill = $env:CMD_SKILL })
            $json = $targets | ConvertTo-Json -Compress -AsArray
            "targets=$json" >> $env:GITHUB_OUTPUT
            "count=$($targets.Count)" >> $env:GITHUB_OUTPUT
            return
          }

          # Detect changed files between base and head
          $diff = git diff --name-only "$env:PR_BASE_SHA" "$env:PR_HEAD_SHA" 2>$null
          if ($LASTEXITCODE -ne 0) {
            # Fallback: diff against merge-base
            $mergeBase = git merge-base "$env:PR_BASE_SHA" "$env:PR_HEAD_SHA"
            $diff = git diff --name-only $mergeBase "$env:PR_HEAD_SHA"
          }

          $changedFiles = $diff -split "`n" | Where-Object { $_ }

          # Collect unique plugin/skill pairs from changed paths
          $seen = @{}
          $pluginWide = @{}
          $targets = @()

          foreach ($file in $changedFiles) {
            # Match plugins/<plugin>/skills/<skill>/...
            if ($file -match '^plugins/([^/]+)/skills/([^/]+)/') {
              $key = "$($Matches[1])/$($Matches[2])"
              if (-not $seen.ContainsKey($key)) {
                $seen[$key] = $true
                $targets += [PSCustomObject]@{ Plugin = $Matches[1]; Skill = $Matches[2] }
              }
            }
            # Match tests/<plugin>/<skill>/...
            elseif ($file -match '^tests/([^/]+)/([^/]+)/') {
              $key = "$($Matches[1])/$($Matches[2])"
              if (-not $seen.ContainsKey($key)) {
                $seen[$key] = $true
                $targets += [PSCustomObject]@{ Plugin = $Matches[1]; Skill = $Matches[2] }
              }
            }
            # Match plugins/<plugin>/ level changes (plugin.json etc.) - run all skills
            elseif ($file -match '^plugins/([^/]+)/[^/]+$') {
              $pluginWide[$Matches[1]] = $true
            }
          }

          # For plugin-wide changes, replace per-skill targets with a single plugin-wide target
          foreach ($plugin in $pluginWide.Keys) {
            $targets = @($targets | Where-Object { $_.Plugin -ne $plugin })
            $targets += [PSCustomObject]@{ Plugin = $plugin; Skill = '' }
          }

          if ($targets.Count -eq 0) {
            Write-Host "No plugin/skill changes detected."
            "count=0" >> $env:GITHUB_OUTPUT
            "targets=[]" >> $env:GITHUB_OUTPUT
            return
          }

          Write-Host "Detected $($targets.Count) target(s):"
          $targets | ForEach-Object { Write-Host "  - $($_.Plugin)$(if ($_.Skill) { "/$($_.Skill)" })" }

          $json = $targets | ConvertTo-Json -Compress -AsArray
          "targets=$json" >> $env:GITHUB_OUTPUT
          "count=$($targets.Count)" >> $env:GITHUB_OUTPUT

      - name: Run skill coverage
        if: steps.detect.outputs.count != '0'
        id: coverage
        shell: pwsh
        env:
          TARGETS_JSON: ${{ steps.detect.outputs.targets }}
        run: |
          $targets = $env:TARGETS_JSON | ConvertFrom-Json
          $allJson = @()
          $summary = @()

          # Run the trusted script from base branch against PR content in the worktree
          $scriptPath = "$env:GITHUB_WORKSPACE/eng/skill-coverage/Measure-SkillCoverage.ps1"
          $prRoot = "$env:GITHUB_WORKSPACE/pr-head"

          foreach ($t in $targets) {
            $args = @{ Format = 'Json'; RepoRoot = $prRoot }

            if ($t.Plugin) { $args.PluginName = $t.Plugin }
            if ($t.Skill) { $args.SkillName = $t.Skill }

            Write-Host "::group::Coverage: $($t.Plugin)$(if ($t.Skill) { "/$($t.Skill)" })"

            try {
              $result = & $scriptPath @args
              $parsed = ($result | Out-String) | ConvertFrom-Json

              # Handle single or array results
              $reports = if ($parsed -is [array]) { $parsed } else { @($parsed) }

              foreach ($r in $reports) {
                $allJson += $r
                if ($r.coverageMode -eq 'consumer') {
                  $summary += "| :information_source: | ``$($r.plugin)`` | ``$($r.skill)`` | - | **N/A (reference-only)** |"
                  continue
                }

                $pct = $r.summary.percentage
                $icon = if ($pct -ge 80) { ':white_check_mark:' }
                        elseif ($pct -ge 50) { ':warning:' }
                        else { ':x:' }
                $summary += "| $icon | ``$($r.plugin)`` | ``$($r.skill)`` | $($r.summary.coveredPoints)/$($r.summary.totalPoints) | **$pct%** |"
              }
            }
            catch {
              Write-Host "::warning::Failed to analyze $($t.Plugin)/$($t.Skill): $_"
              $summary += "| :grey_question: | ``$($t.Plugin)`` | ``$($t.Skill)`` | — | error |"
            }

            Write-Host "::endgroup::"
          }

          # Build markdown report
          $md = @()
          $md += '## Skill Coverage Report'
          $md += ''
          $md += '| | Plugin | Skill | Covered | Coverage |'
          $md += '|---|--------|-------|---------|----------|'
          $md += $summary
          $md += ''

          # Add uncovered items details if any
          $uncoveredDetails = @()
          foreach ($r in $allJson) {
            if ($r.coverageMode -ne 'consumer' -and $r.uncovered.Count -gt 0) {
              $uncoveredDetails += "<details><summary>Uncovered: <code>$($r.plugin)/$($r.skill)</code></summary>"
              $uncoveredDetails += ''
              foreach ($u in $r.uncovered) {
                $uncoveredDetails += "- **[$($u.category)]** $($u.description) (line $($u.line))"
              }
              $uncoveredDetails += ''
              $uncoveredDetails += '</details>'
              $uncoveredDetails += ''
            }
          }
          if ($uncoveredDetails.Count -gt 0) {
            $md += $uncoveredDetails
          }

          # Write the report to a file for the comment job
          $report = $md -join "`n"
          $report | Out-File -FilePath coverage-report.md -Encoding utf8

          # Also write to step summary
          $report >> $env:GITHUB_STEP_SUMMARY

      - name: Upload coverage report
        if: steps.detect.outputs.count != '0'
        uses: actions/upload-artifact@043fb46d1a93c77aae656e7c1c64a875d1fc6a0a # v7
        with:
          name: coverage-report
          path: coverage-report.md
          retention-days: 1

  # ──────────────────────────────────────────────────────────────
  #  Job 2: Comment — posts results with write permissions only.
  #         No PR code is checked out or executed in this job.
  # ──────────────────────────────────────────────────────────────
  comment:
    needs: analyze
    if: >-
      needs.analyze.outputs.count != '0' &&
      (github.event_name != 'pull_request' ||
       github.event.pull_request.head.repo.full_name == github.repository)
    runs-on: ubuntu-latest
    permissions:
      pull-requests: write
      issues: write

    steps:
      - name: Download coverage report
        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8
        with:
          name: coverage-report

      - name: Post or update PR comment
        uses: actions/github-script@373c709c69115d41ff229c7e5df9f8788daa9553 # v9
        env:
          PR_NUMBER: ${{ needs.analyze.outputs.pr_number }}
        with:
          script: |
            const fs = require('fs');
            const body = fs.readFileSync('coverage-report.md', 'utf8');
            const marker = '<!-- skill-coverage-report -->';
            const fullBody = `${marker}\n${body}`;
            const prNumber = parseInt(process.env.PR_NUMBER, 10);

            // Paginate to find existing marker comment (handles PRs with >100 comments)
            const comments = await github.paginate(github.rest.issues.listComments, {
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: prNumber,
              per_page: 100
            });

            const existing = comments.find(c => c.body && c.body.startsWith(marker));

            if (existing) {
              await github.rest.issues.updateComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                comment_id: existing.id,
                body: fullBody
              });
              core.info(`Updated comment ${existing.id}`);
            } else {
              await github.rest.issues.createComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: prNumber,
                body: fullBody
              });
              core.info('Created new coverage comment');
            }

      - name: Post no-changes comment
        if: needs.analyze.outputs.count == '0' && github.event_name == 'issue_comment'
        continue-on-error: true
        uses: actions/github-script@373c709c69115d41ff229c7e5df9f8788daa9553 # v9
        with:
          script: |
            await github.rest.issues.createComment({
              owner: context.repo.owner,
              repo: context.repo.repo,
              issue_number: context.issue.number,
              body: '**Skill Coverage:** No plugin/skill changes detected in this PR. Use `/skill-coverage <plugin> [skill]` to target specific skills.'
            });