import logging
import time
from typing import List, Tuple

import groq

import config
from models import Match, Receipt, Transaction

# Set up logging
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)


class AIMatcher:
    def __init__(self, use_batch_matching=True):
        self.client = groq.Groq(api_key=config.GROQ_API_KEY)
        self.model = "llama3-8b-8192"
        self.max_retries = 3
        self.retry_delay = 2  # seconds - increased for rate limiting
        self.rate_limit_delay = 1.0  # seconds between API calls
        self.last_api_call = 0
        self.use_batch_matching = (
            use_batch_matching  # Toggle between new and legacy methods
        )

    def match_receipts_to_transactions(
        self, receipts: List[Receipt], transactions: List[Transaction]
    ) -> List[Match]:
        """Match receipts to transactions using AI"""
        logger.info(
            f"Starting AI matching for {len(receipts)} receipts against {len(transactions)} transactions"
        )
        matches = []

        for i, receipt in enumerate(receipts):
            logger.info(
                f"Processing receipt {i + 1}/{len(receipts)}: {receipt.vendor} - ${receipt.amount}"
            )

            # Rate limiting
            self._rate_limit()

            # Get the BEST match for this receipt (highest confidence score)
            best_match = self._find_best_match(receipt, transactions)
            if best_match:
                matches.append(best_match)
                logger.info(
                    f"Found match: {best_match.confidence_score:.3f} - {best_match.match_reason}"
                )
            else:
                logger.warning(
                    f"No match found for receipt: {receipt.vendor} - ${receipt.amount}"
                )

        # Sort by confidence score (highest first)
        matches = sorted(matches, key=lambda x: x.confidence_score, reverse=True)
        logger.info(f"AI matching completed. Found {len(matches)} matches")
        return matches

    def _rate_limit(self):
        """Implement rate limiting to avoid API quota exhaustion"""
        current_time = time.time()
        time_since_last_call = current_time - self.last_api_call

        if time_since_last_call < self.rate_limit_delay:
            sleep_time = self.rate_limit_delay - time_since_last_call
            logger.debug(f"Rate limiting: sleeping for {sleep_time:.2f} seconds")
            time.sleep(sleep_time)

        self.last_api_call = time.time()

    def _find_best_match(
        self, receipt: Receipt, transactions: List[Transaction]
    ) -> Match:
        """Find the BEST match for a receipt using a single AI call for all candidates"""
        candidates = self._filter_candidates(receipt, transactions)
        if not candidates:
            logger.warning(
                f"No candidates found for receipt: {receipt.vendor} - ${receipt.amount}"
            )
            return None

        logger.info(f"Found {len(candidates)} candidates for receipt: {receipt.vendor}")

        # Choose matching method based on configuration
        if self.use_batch_matching:
            # New efficient method: single AI call for all candidates
            best_match = self._find_best_match_single_call(receipt, candidates)
        else:
            # Legacy method: individual AI calls (fallback)
            best_match = self._find_best_match_legacy(receipt, candidates)

        return best_match

    def _find_best_match_single_call(
        self, receipt: Receipt, candidates: List[Transaction]
    ) -> Match:
        """Find the best match using a single AI call to evaluate all candidates"""
        if not candidates:
            return None

        # Limit candidates to avoid token limits (adjust based on your needs)
        max_candidates = 10
        if len(candidates) > max_candidates:
            # Sort by amount similarity and take top candidates
            candidates = sorted(
                candidates, key=lambda t: abs(receipt.amount - abs(t.amount))
            )[:max_candidates]
            logger.info(
                f"Limited candidates to top {max_candidates} by amount similarity"
            )

        # Build comprehensive prompt with all candidates
        candidates_text = ""
        for i, transaction in enumerate(candidates):
            transaction_amount_abs = abs(transaction.amount)
            date_diff = abs((receipt.receipt_date - transaction.transaction_date).days)
            amount_diff = abs(receipt.amount - transaction_amount_abs)
            amount_percent_diff = (
                (amount_diff / receipt.amount) * 100 if receipt.amount > 0 else 0
            )

            candidates_text += f"""
Candidate {i + 1}:
- Vendor: {transaction.vendor}
- Amount: ${transaction.amount} (absolute: ${transaction_amount_abs})
- Date: {transaction.transaction_date.strftime("%Y-%m-%d")} ({date_diff} days difference)
- Notes: {transaction.notes}
- Amount difference: ${amount_diff} ({amount_percent_diff:.1f}%)
"""

        prompt = f"""
You are an expert at matching receipts to bank transactions. Analyze the receipt below against ALL the candidate transactions and return the BEST match.

RECEIPT TO MATCH:
- Vendor: {receipt.vendor}
- Amount: ${receipt.amount}
- Date: {receipt.receipt_date.strftime("%Y-%m-%d")}
- Description: {receipt.description}
- Category: {receipt.category}

CANDIDATE TRANSACTIONS:
{candidates_text}

SCORING CRITERIA:
- Perfect matches (same vendor, amount, date): 0.95-1.0
- High confidence (minor differences): 0.8-0.94
- Medium confidence (moderate differences): 0.6-0.79
- Low confidence (significant differences): 0.4-0.59
- Very low confidence (major differences): 0.2-0.39
- Minimal similarity: 0.1-0.19
- No meaningful similarity: 0.0-0.09

Consider vendor name similarity, amount accuracy, date proximity, and description/notes relevance.

IMPORTANT: You MUST return the candidate with the highest match score, even if it's very low. Never return NONE.
Return ONLY the best match in this exact format:
CANDIDATE_NUMBER|CONFIDENCE_SCORE|REASON

Example: 3|0.87|Same vendor name, exact amount match, 1 day apart
Example of low match: 5|0.15|Best available option despite significant differences in vendor and amount
"""

        for attempt in range(self.max_retries):
            try:
                result = self._call_groq_api_with_timeout(
                    prompt, timeout=45
                )  # Longer timeout for complex prompt

                # Parse the single result
                candidate_num, score, reason = self._parse_single_match_response(result)

                if candidate_num == -1:  # Parsing error occurred
                    logger.warning(
                        f"Failed to parse AI response for receipt: {receipt.vendor}"
                    )
                    return None

                if 0 <= candidate_num < len(candidates):
                    best_transaction = candidates[candidate_num]
                    logger.info(
                        f"AI selected candidate {candidate_num + 1}: {best_transaction.vendor} (score: {score:.3f})"
                    )
                    return Match(receipt, best_transaction, score, reason)
                else:
                    logger.warning(
                        f"AI returned invalid candidate number: {candidate_num}"
                    )
                    return None

            except Exception as e:
                logger.warning(
                    f"Attempt {attempt + 1} failed for receipt {receipt.id}: {str(e)}"
                )
                if attempt < self.max_retries - 1:
                    sleep_time = self.retry_delay * (2**attempt)
                    logger.info(f"Waiting {sleep_time} seconds before retry...")
                    time.sleep(sleep_time)
                else:
                    logger.error(f"All attempts failed for receipt {receipt.id}")
                    return None

        return None

    def _parse_single_match_response(self, result: str) -> Tuple[int, float, str]:
        """Parse AI response for single best match"""
        result = result.strip()
        logger.debug(f"Parsing single match response: {result}")

        try:
            if result.upper().startswith("NONE"):
                # This should not happen with new prompt, but handle as parsing error
                logger.warning(
                    "AI returned NONE despite being instructed to always return best match"
                )
                return -1, 0.0, "AI returned NONE unexpectedly"

            if "|" in result:
                parts = result.split("|")
                if len(parts) >= 3:
                    candidate_str = parts[0].strip()
                    score_str = parts[1].strip()
                    reason = "|".join(parts[2:]).strip()

                    # Extract candidate number
                    import re

                    candidate_match = re.search(r"\d+", candidate_str)
                    if candidate_match:
                        candidate_num = (
                            int(candidate_match.group()) - 1
                        )  # Convert to 0-based index
                    else:
                        raise ValueError("No candidate number found")

                    # Extract score
                    score_clean = "".join(
                        c for c in score_str if c.isdigit() or c == "."
                    )
                    score = float(score_clean) if score_clean else 0.0

                    # Ensure score is in valid range
                    score = max(0.0, min(1.0, score))

                    logger.debug(
                        f"Parsed: candidate={candidate_num}, score={score}, reason={reason}"
                    )
                    return candidate_num, score, reason

        except Exception as e:
            logger.warning(f"Error parsing single match response: {e}")

        # Fallback
        logger.warning(f"Could not parse single match response: {result}")
        return -1, 0.0, f"Parse error: {result[:50]}..."

    def _filter_candidates(
        self, receipt: Receipt, transactions: List[Transaction]
    ) -> List[Transaction]:
        """Filter transactions to create a reasonable candidate list"""
        candidates = []
        amount_threshold = receipt.amount * 2.0  # 200% threshold - very inclusive

        for transaction in transactions:
            # Use absolute value for transaction amount comparison
            transaction_amount_abs = abs(transaction.amount)

            # Only exclude transactions with obviously different amounts
            if abs(receipt.amount - transaction_amount_abs) <= amount_threshold:
                candidates.append(transaction)

        logger.debug(
            f"Filtered {len(transactions)} transactions to {len(candidates)} candidates"
        )
        return candidates

    def _find_best_match_legacy(
        self, receipt: Receipt, transactions: List[Transaction]
    ) -> Match:
        """Legacy method: Find the best match using individual API calls (kept as fallback)"""
        candidates = self._filter_candidates(receipt, transactions)
        if not candidates:
            return None

        best_match = None
        highest_score = 0

        for transaction in candidates:
            score, reason = self._calculate_match_score(receipt, transaction)
            logger.debug(
                f"Score {score:.3f} for transaction {transaction.vendor}: {reason}"
            )

            if score > highest_score:
                highest_score = score
                best_match = Match(receipt, transaction, score, reason)

        return best_match

    def _calculate_match_score(
        self, receipt: Receipt, transaction: Transaction
    ) -> Tuple[float, str]:
        """Calculate match score using AI"""
        # Calculate differences for the AI to consider
        date_diff = abs((receipt.receipt_date - transaction.transaction_date).days)
        transaction_amount_abs = abs(transaction.amount)
        amount_diff = abs(receipt.amount - transaction_amount_abs)
        amount_percent_diff = (
            (amount_diff / receipt.amount) * 100 if receipt.amount > 0 else 0
        )

        prompt = f"""
        Compare this receipt with this transaction and provide a confidence score (0-1) and brief reason, the reason must be a single sentence without any special formatting.
        
        Receipt: {receipt.vendor}, ${receipt.amount}, {receipt.receipt_date.strftime("%Y-%m-%d")}
        Receipt Description: {receipt.description}
        Receipt Category: {receipt.category}
        Transaction: {transaction.vendor}, ${transaction.amount} (absolute: ${transaction_amount_abs}), {transaction.transaction_date.strftime("%Y-%m-%d")}
        Transaction Notes: {transaction.notes}
        
        Differences:
        - Date difference: {date_diff} days
        - Amount difference: ${amount_diff} ({amount_percent_diff:.1f}%)
        - Vendor comparison: "{receipt.vendor}" vs "{transaction.vendor}"
        - Description/Notes comparison: "{receipt.description}" vs "{transaction.notes}"
        - Category: {receipt.category}
        
        Score this potential match based on how likely it is the correct match:
        
        - Perfect matches (same vendor, amount, date): 0.95-1.0
        - High confidence (minor differences): 0.8-0.94
        - Medium confidence (moderate differences): 0.6-0.79
        - Low confidence (significant differences): 0.4-0.59
        - Very low confidence (major differences): 0.2-0.39
        - Minimal similarity: 0.1-0.19
        - No meaningful similarity: 0.0-0.09
        
        Consider description and category similarity in your scoring.
        
        IMPORTANT: Return ONLY the score and reason separated by a pipe character.
        Format: [score]|[reason]
        Example: 0.85|Same vendor, same amount, 2 days apart
        """

        for attempt in range(self.max_retries):
            try:
                result = self._call_groq_api_with_timeout(
                    prompt, timeout=30
                )  # Increased timeout

                # Parse the result - handle multiple formats
                score, reason = self._parse_ai_response(result)

                logger.debug(f"AI Response: {result}")
                logger.debug(f"Parsed: score={score}, reason={reason}")

                return score, reason

            except Exception as e:
                logger.warning(
                    f"Attempt {attempt + 1} failed for receipt {receipt.id}: {str(e)}"
                )
                if attempt < self.max_retries - 1:
                    # Exponential backoff for rate limiting
                    sleep_time = self.retry_delay * (2**attempt)
                    logger.info(f"Waiting {sleep_time} seconds before retry...")
                    time.sleep(sleep_time)
                else:
                    logger.error(f"All attempts failed for receipt {receipt.id}")
                    return 0.0, f"AI error after {self.max_retries} attempts: {str(e)}"

    def _parse_ai_response(self, result: str) -> Tuple[float, str]:
        """Parse AI response with robust error handling"""
        result = result.strip()
        logger.debug(f"Parsing AI response: {result}")

        # Try to find score in various formats
        if "|" in result:
            parts = result.split("|")
            logger.debug(f"Split response into {len(parts)} parts: {parts}")

            # Look for a numeric score in any part
            for i, part in enumerate(parts):
                part = part.strip()
                try:
                    # Remove any non-numeric characters except decimal point
                    score_str_clean = "".join(
                        c for c in part if c.isdigit() or c == "."
                    )
                    if score_str_clean:
                        score = float(score_str_clean)
                        if 0 <= score <= 1:  # Valid confidence score
                            # Get reason from other parts
                            reason_parts = [
                                p.strip()
                                for j, p in enumerate(parts)
                                if j != i and p.strip()
                            ]
                            reason = (
                                " | ".join(reason_parts)
                                if reason_parts
                                else "Score extracted"
                            )
                            logger.debug(
                                f"Found score {score} in part {i}, reason: {reason}"
                            )
                            return score, reason
                except ValueError:
                    continue

        # Try to extract just a number from the response
        try:
            import re

            numbers = re.findall(r"\d+\.?\d*", result)
            if numbers:
                for num_str in numbers:
                    score = float(num_str)
                    if 0 <= score <= 1:  # Valid confidence score
                        logger.debug(f"Extracted score {score} from response")
                        return score, f"Extracted from response: {result[:50]}..."
        except (ValueError, IndexError):
            pass

        # Fallback - try to find any number and normalize it
        try:
            import re

            numbers = re.findall(r"\d+\.?\d*", result)
            if numbers:
                score = float(numbers[0])
                # Normalize to 0-1 range if it's a percentage or other scale
                if score > 1:
                    score = score / 100  # Assume percentage
                score = max(0, min(1, score))  # Clamp to 0-1
                logger.debug(f"Normalized score {score} from response")
                return score, f"Normalized from response: {result[:50]}..."
        except (ValueError, IndexError):
            pass

        # Final fallback
        logger.warning(f"Could not parse AI response: {result}")
        return 0.0, f"Unparseable response: {result[:50]}..."

    def _call_groq_api_with_timeout(self, prompt: str, timeout: int = 15) -> str:
        """Make API call with timeout and retry logic"""
        import concurrent.futures

        def api_call():
            try:
                response = self.client.chat.completions.create(
                    model=self.model,
                    messages=[{"role": "user", "content": prompt}],
                    max_tokens=200,
                    temperature=0.1,
                )
                return response.choices[0].message.content.strip()
            except Exception as e:
                raise e

        try:
            with concurrent.futures.ThreadPoolExecutor() as executor:
                future = executor.submit(api_call)
                return future.result(timeout=timeout)
        except concurrent.futures.TimeoutError:
            raise Exception(f"API call timed out after {timeout} seconds")
        except Exception as e:
            raise e