#!/usr/bin/env bash
# Required env vars: AI_API_URL, AI_API_KEY, AI_MODEL, PR_TITLE, PR_BODY
# Optional env vars: PREV_REVIEW, INCREMENTAL
# Reads: pr.diff, prompts/review.md (or prompts/review-update.md for incremental)
# Writes: $GITHUB_OUTPUT (review)
set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
PROMPTS_DIR="${SCRIPT_DIR}/../prompts"

DIFF=$(cat pr.diff)
echo "Diff size: $(wc -c < pr.diff) bytes"

if [ "${INCREMENTAL:-false}" = "true" ] && [ -n "${PREV_REVIEW:-}" ]; then
  echo "Building incremental review with conversation history"
  SYSTEM_PROMPT=$(cat "${PROMPTS_DIR}/review-update.md")

  # Reconstruct conversation: the model previously reviewed an earlier state,
  # now we show it only what changed since then.
  MESSAGES=$(jq -n \
    --arg system "$SYSTEM_PROMPT" \
    --arg prev "$PREV_REVIEW" \
    --arg title "$PR_TITLE" \
    --arg body "$PR_BODY" \
    --arg diff "$DIFF" \
    '[
      { role: "system", content: $system },
      { role: "assistant", content: $prev },
      { role: "user", content: ("The PR has been updated. Here are the new changes since your last review.\n\nPR Title: " + $title + "\nPR Description: " + $body + "\n\nIncremental diff:\n```diff\n" + $diff + "\n```\n\nUpdate your review, keeping previous feedback relevant to unchanged code and focusing new commentary on what has changed.") }
    ]')
else
  echo "Building full review"
  SYSTEM_PROMPT=$(cat "${PROMPTS_DIR}/review.md")

  MESSAGES=$(jq -n \
    --arg system "$SYSTEM_PROMPT" \
    --arg title "$PR_TITLE" \
    --arg body "$PR_BODY" \
    --arg diff "$DIFF" \
    '[
      { role: "system", content: $system },
      { role: "user", content: ("PR Title: " + $title + "\nPR Description: " + $body + "\n\nDiff:\n```diff\n" + $diff + "\n```") }
    ]')
fi

PAYLOAD=$(jq -n \
  --arg model "$AI_MODEL" \
  --argjson messages "$MESSAGES" \
  '{
    model: $model,
    messages: $messages,
    max_tokens: 1024,
    temperature: 0.2
  }')

echo "Payload size: $(echo "$PAYLOAD" | wc -c) bytes"
echo "Calling endpoint: ${AI_API_URL%/}/chat/completions"
echo "Model: ${AI_MODEL}"

HTTP_RESPONSE=$(curl -s \
  --max-time 120 \
  -w "\n__HTTP_STATUS__:%{http_code}" \
  -H "Authorization: Bearer ${AI_API_KEY}" \
  -H "Content-Type: application/json" \
  -d "$PAYLOAD" \
  "${AI_API_URL%/}/chat/completions")
CURL_EXIT=$?

HTTP_STATUS=$(echo "$HTTP_RESPONSE" | grep '__HTTP_STATUS__:' | cut -d: -f2)
RESPONSE_BODY=$(echo "$HTTP_RESPONSE" | sed '/__HTTP_STATUS__:/d')

echo "curl exit code: ${CURL_EXIT}"
echo "HTTP status: ${HTTP_STATUS}"
echo "Response body: ${RESPONSE_BODY}"

if [ "$CURL_EXIT" -ne 0 ]; then
  echo "::error::curl failed with exit code ${CURL_EXIT}"
  exit 1
fi

if [ "$HTTP_STATUS" -lt 200 ] || [ "$HTTP_STATUS" -ge 300 ]; then
  echo "::error::API returned HTTP ${HTTP_STATUS}: ${RESPONSE_BODY}"
  exit 1
fi

REVIEW=$(echo "$RESPONSE_BODY" | jq -r '.choices[0].message.content')
if [ -z "$REVIEW" ] || [ "$REVIEW" = "null" ]; then
  echo "::error::Failed to extract review from response. Full body: ${RESPONSE_BODY}"
  exit 1
fi

echo "Review length: $(echo "$REVIEW" | wc -c) chars"
echo "review<<EOF" >> "$GITHUB_OUTPUT"
echo "$REVIEW" >> "$GITHUB_OUTPUT"
echo "EOF" >> "$GITHUB_OUTPUT"