import os
import hashlib
import boto3
import sqlite3
import json
import argparse
import glob
import tempfile
import datetime
import posixpath
import smart_open

from dataclasses import dataclass
from pypdf import PdfReader
from tqdm import tqdm
from typing import Optional, List, Tuple, Dict
from urllib.parse import urlparse
from concurrent.futures import ProcessPoolExecutor, as_completed

from pdelfin.data.renderpdf import render_pdf_to_base64png
from pdelfin.prompts import build_finetuning_prompt
from pdelfin.prompts.anchor import get_anchor_text

# Global s3 client for the whole script, feel free to adjust params if you need it
s3 = boto3.client('s3')

class DatabaseManager:
    @dataclass(frozen=True)
    class BatchInferenceRecord:
        inference_s3_path: str
        pdf_s3_path: str
        page_num: int  # 1 indexed!
        start_index: int
        length: int
        finish_reason: str
        error: Optional[str]

        def is_usable(self):
            return self.error is None and self.finish_reason == "stop"

    @dataclass(frozen=True)
    class PDFRecord:
        s3_path: str
        num_pages: int
        status: str

    def __init__(self, s3_workspace: str):
        cache_key = hashlib.sha256(s3_workspace.strip().lower().encode('utf-8')).hexdigest()
        home_cache_dir = os.path.join(os.path.expanduser('~'), '.cache', 'pdelfin', cache_key)
        os.makedirs(home_cache_dir, exist_ok=True)
        self.db_path = os.path.join(home_cache_dir, 'index.db')
        
        self.conn = sqlite3.connect(self.db_path)
        self.cursor = self.conn.cursor()
        self._initialize_tables()

    def _initialize_tables(self):
        self.cursor.execute("""
            CREATE TABLE IF NOT EXISTS page_results (
                inference_s3_path TEXT,
                pdf_s3_path TEXT,
                page_num INTEGER,
                start_index BIGINT,
                length BIGINT,
                finish_reason TEXT,
                error TEXT
            )
        """)
        self.cursor.execute("""
            CREATE INDEX IF NOT EXISTS idx_path ON page_results(s3_path)
        """)
        self.cursor.execute("""
            CREATE TABLE IF NOT EXISTS pdfs (
                s3_path TEXT PRIMARY KEY,
                num_pages INTEGER,
                status TEXT DEFAULT 'pending'
            )
        """)
        self.cursor.execute("""
            CREATE TABLE IF NOT EXISTS processed_files (
                s3_path TEXT PRIMARY KEY,
                etag TEXT
            )
        """)
        # Generic metadata such as current round
        self.cursor.execute("""
            CREATE TABLE IF NOT EXISTS metadata (
                key TEXT PRIMARY KEY,
                value TEXT
            )
        """)

        self.conn.commit()

    def get_metadata(self, key: str) -> Optional[str]:
        self.cursor.execute("SELECT value FROM metadata WHERE key=?", (key,))
        result = self.cursor.fetchone()
        return result[0] if result else None
    
    def set_metadata(self, key: str, value: str) -> None:
        self.cursor.execute("""
            INSERT INTO metadata (key, value)
            VALUES (?, ?)
            ON CONFLICT(key) DO UPDATE SET value=excluded.value
        """, (key, value))
        self.conn.commit()

    def get_current_round(self):
        round_value = self.get_metadata("round")
        return int(round_value) if round_value else 0

    def is_file_processed(self, s3_path, etag):
        self.cursor.execute("SELECT etag FROM processed_files WHERE s3_path = ?", (s3_path,))
        result = self.cursor.fetchone()
        return result is not None and result[0] == etag

    def add_index_entries(self, index_entries: List[BatchInferenceRecord]):
        if index_entries:
            self.cursor.executemany("""
                INSERT INTO page_results (inference_s3_path, pdf_s3_path, page_num, start_index, length, finish_reason, error)
                VALUES (?, ?, ?, ?, ?, ?)
            """, [(entry.inference_s3_path, entry.pdf_s3_path, entry.page_num, entry.start_index, entry.length, entry.finish_reason, entry.error) for entry in index_entries])
            self.conn.commit()

    def get_index_entries(self, s3_path: str) -> List[BatchInferenceRecord]:
        self.cursor.execute("""
            SELECT inference_s3_path, pdf_s3_path, page_num, start_index, length, finish_reason, error
            FROM page_results
            WHERE s3_path = ?
            ORDER BY inference_s3_path DESC start_index ASC page_num ASC
        """, (s3_path,))
        
        rows = self.cursor.fetchall()
        
        return [
            self.BatchInferenceRecord(
                inference_s3_path=row[0],
                pdf_s3_path=row[1],
                page_num=row[2],
                start_index=row[3],
                length=row[4],
                finish_reason=row[5],
                error=row[6]
            )
            for row in rows
        ]

    def update_processed_file(self, s3_path, etag):
        self.cursor.execute("""
            INSERT INTO processed_files (s3_path, etag)
            VALUES (?, ?)
            ON CONFLICT(s3_path) DO UPDATE SET etag=excluded.etag
        """, (s3_path, etag))
        self.conn.commit()

    def pdf_exists(self, s3_path: str) -> bool:
        self.cursor.execute("SELECT 1 FROM pdfs WHERE s3_path = ?", (s3_path,))
        return self.cursor.fetchone() is not None

    def add_pdf(self, s3_path: str, num_pages: int, status: str = 'pending') -> None:
        try:
            self.cursor.execute("""
                INSERT INTO pdfs (s3_path, num_pages, status)
                VALUES (?, ?, ?)
            """, (s3_path, num_pages, status))
            self.conn.commit()
        except sqlite3.IntegrityError:
            print(f"PDF with s3_path '{s3_path}' already exists.")

    def get_pdf(self, s3_path: str) -> Optional[PDFRecord]:
        self.cursor.execute("""
            SELECT s3_path, num_pages, status
            FROM pdfs
            WHERE s3_path = ?
        """, (s3_path,))
        
        row = self.cursor.fetchone()
        
        if row:
            return self.PDFRecord(
                s3_path=row[0],
                num_pages=row[1],
                status=row[2]
            )
        return None
    
    def get_pdfs_by_status(self, status: str) -> List[PDFRecord]:
        self.cursor.execute("""
            SELECT s3_path, num_pages, status
            FROM pdfs
            WHERE status == ?
            ORDER BY s3_path DESC
        """, (status, ))
        
        rows = self.cursor.fetchall()
        
        return [
            self.PDFRecord(
                s3_path=row[0],
                num_pages=row[1],
                status=row[2]
            )
            for row in rows
        ]

    def close(self):
        self.conn.close()


# Writes batches of lines out to a set of files, keeping each file below some maximum size
class BatchWriter:
    def __init__(self, output_prefix: str, max_size_mb: int = 250):
        self.output_prefix = output_prefix
        self.max_size = max_size_mb * 1024 * 1024  # Convert MB to bytes
        self.batch = []
        self.batch_size = 0

        parsed = urlparse(output_prefix)
        self.is_s3 = parsed.scheme in ('s3', 's3a', 's3n')

        if not self.is_s3:
            os.makedirs(output_prefix, exist_ok=True)

    def _compute_hash(self, content: str) -> str:
        """Compute a 20-character SHA1 hash of the given content."""
        sha1 = hashlib.sha1()
        sha1.update(content.encode('utf-8'))
        return sha1.hexdigest()[:20]

    def _get_output_path(self, hash_str: str) -> str:
        """Generate the full output path with hash in the filename."""
        parsed = urlparse(self.output_prefix)
        if self.is_s3:
            bucket = parsed.netloc
            key = parsed.path.lstrip('/')
            if key and not key.endswith('/'):
                key += '/'
            full_key = posixpath.join(key, f"output_{hash_str}.jsonl")
            return f"s3://{bucket}/{full_key}"
        else:
            filename = f"output_{hash_str}.jsonl"
            return os.path.join(self.output_prefix, filename)

    def write_line(self, line: str):
        line_size = len(line.encode('utf-8')) + 1  # +1 for newline

        if self.batch_size + line_size > self.max_size:
            self._write_batch()
        
        self.batch.append(line)
        self.batch_size += line_size

    def _write_batch(self):
        if not self.batch:
            return

        batch_content = "\n".join(self.batch) + "\n"
        hash_str = self._compute_hash(batch_content)
        output_path = self._get_output_path(hash_str)

        with smart_open.open(output_path, 'w') as f_out:
            f_out.write(batch_content)
        print(f"Wrote batch to {output_path}")

        self.batch = []
        self.batch_size = 0

    def close(self):
        self._write_batch()


def parse_s3_path(s3_path):
    if not s3_path.startswith('s3://'):
        raise ValueError('s3_path must start with s3://')
    path = s3_path[5:]
    bucket, _, prefix = path.partition('/')
    return bucket, prefix

def expand_s3_glob(s3_glob: str) -> Dict[str, str]:
    parsed = urlparse(s3_glob)
    bucket_name = parsed.netloc
    prefix = os.path.dirname(parsed.path.lstrip('/')).rstrip('/') + "/"
    pattern = os.path.basename(parsed.path)

    paginator = s3.get_paginator('list_objects_v2')
    page_iterator = paginator.paginate(Bucket=bucket_name, Prefix=prefix)

    matched_files = {}
    for page in page_iterator:
        for obj in page.get('Contents', []):
            key = obj['Key']
            if glob.fnmatch.fnmatch(key, posixpath.join(prefix, pattern)):
                matched_files[f"s3://{bucket_name}/{key}"] = obj['ETag'].strip('"')

    return matched_files

def build_page_query(local_pdf_path: str, pretty_pdf_path: str, page: int) -> dict:
    image_base64 = render_pdf_to_base64png(local_pdf_path, page, 1024)
    anchor_text = get_anchor_text(local_pdf_path, page, pdf_engine="pdfreport")

    return {
        "custom_id": f"{pretty_pdf_path}-{page}",
        "chat_messages": [
            {
                "role": "user",
                "content": [
                    {"type": "text", "text": build_finetuning_prompt(anchor_text)},
                    {"type": "image_url", "image_url": {"url": f"data:image/png;base64,{image_base64}"}}
                ],
            }
        ],
        "temperature": 0.8,
        "max_tokens": 6000,
    }


def get_s3_bytes(s3_path: str, start_index: Optional[int] = None, end_index: Optional[int] = None) -> bytes:
    bucket, key = parse_s3_path(s3_path)

    # Build the range header if start_index and/or end_index are specified
    range_header = None
    if start_index is not None or end_index is not None:
        range_value = f"bytes={start_index or 0}-"
        if end_index is not None:
            range_value += str(end_index)
        range_header = {'Range': range_value}

    if range_header:
        obj = s3.get_object(Bucket=bucket, Key=key, Range=range_header['Range'])
    else:
        obj = s3.get_object(Bucket=bucket, Key=key)

    return obj['Body'].read()


def parse_custom_id(custom_id: str) -> Tuple[str, int]:
    s3_path = custom_id[:custom_id.rindex("-")]
    page_num = int(custom_id[custom_id.rindex("-") + 1:])
    return s3_path, page_num

def process_jsonl_content(inference_s3_path: str) -> List[DatabaseManager.BatchInferenceRecord]:
    content = get_s3_bytes(inference_s3_path).decode("utf-8")

    start_index = 0
    index_entries = []
    lines = content.splitlines(keepends=True)
    for line in lines:
        line_length = len(line)

        try:
            data = json.loads(line)
            pdf_s3_path, page_num = parse_custom_id(data["custom_id"])

            assert "outputs" in data and len(data["outputs"]) > 0, "No outputs from model detected"

            index_entries.append(DatabaseManager.BatchInferenceRecord(
                inference_s3_path=inference_s3_path,
                pdf_s3_path=pdf_s3_path,
                page_num=page_num,
                start_index=start_index,
                length=line_length,
                finish_reason=data["outputs"][0]["finish_reason"],
                error=data.get("completion_error", None)
            ))
        except json.JSONDecodeError:
            pass  # Handle JSON decode errors if necessary
        except Exception as e:
            print(f"Error processing line: {e}")

        start_index += line_length

    return index_entries

def get_pdf_num_pages(s3_path: str) -> Optional[int]:
    try:
        with tempfile.NamedTemporaryFile("wb+", suffix=".pdf") as tf:
            tf.write(get_s3_bytes(s3_path))
            tf.flush()

            reader = PdfReader(tf.name)
            return reader.get_num_pages()
    except Exception as ex:
        print(f"Warning, could not add {s3_path} due to {ex}")

    return None

def build_pdf_queries(s3_workspace: str, pdf: DatabaseManager.PDFRecord) -> list[dict]:
    db = DatabaseManager(s3_workspace)

    existing_pages = db.get_index_entries(pdf.s3_path)
    new_queries = []

    # Shortcut out of downloading the actual PDF
    if set(page.page_num for page in existing_pages if page.is_usable()) == set(range(1, pdf.num_pages + 1)):
        return []
    
    try:
        with tempfile.NamedTemporaryFile("wb+", suffix=".pdf") as tf:
            tf.write(get_s3_bytes(pdf.s3_path))
            tf.flush()

            for target_page_num in range(1, pdf.num_pages + 1):
                # Is there an existing page that has no error
                if any(page.is_usable() and page.page_num == target_page_num for page in existing_pages):
                    continue

                # TODO: Later, you may want to retry with different sampling parameters or do something else
                new_queries.append(build_page_query(tf.name, pdf.s3_path, target_page_num))
    except Exception as ex:
        print(f"Warning, could not get batch inferences lines for {pdf.s3_path} due to {ex}")

    return new_queries

def build_dolma_doc(s3_workspace: str, pdf: DatabaseManager.PDFRecord) -> dict:
    db = DatabaseManager(s3_workspace)
    existing_pages = db.get_index_entries(pdf.s3_path)
    document_text = ""
    last_page_start_index = 0
    pdf_page_spans = []

    for target_page_num in range(1, pdf.num_pages + 1):
        target_page = next(page for page in existing_pages if page.is_usable() and page.page_num == target_page_num)

        target_row = get_s3_bytes(target_page.pdf_s3_path,
                                  start_index=target_page.start_index,
                                  end_index=target_page.start_index+target_page.length)
        
        target_data = json.loads(target_row.decode("utf-8"))

        document_text += target_data["natural_text"] + "\n"

        pdf_page_spans.append([last_page_start_index, len(document_text), target_page_num])
        last_page_start_index = len(document_text)

    metadata = {
            "Source-File": pdf.s3_path,
            "pdf-total-pages": pdf.num_pages,
        }
    id_ = hashlib.sha1(document_text.encode()).hexdigest()

    dolma_doc = {
        "id": id_,
        "text": document_text,
        "source": "pdelfin",
        "added": datetime.datetime.now().strftime("%Y-%m-%d"),
        "created": datetime.datetime.now().strftime("%Y-%m-%d"),
        "metadata": metadata,
        "attributes": {
            "pdf_page_numbers": pdf_page_spans
        }
    }

    return dolma_doc


if __name__ == '__main__':
    parser = argparse.ArgumentParser(description='Manager for running millions of PDFs through a batch inference pipeline')
    parser.add_argument('workspace', help='The S3 path where work will be done e.g., s3://bucket/prefix/)')
    parser.add_argument('--add_pdfs', help='Glob path to add PDFs (s3) to the workspace', default=None)
    parser.add_argument('--max_size_mb', type=int, default=250, help='Max file size in MB')
    args = parser.parse_args()

    db = DatabaseManager(args.workspace)
    print(f"Loaded db at {db.db_path}")
    print(f"Current round is {db.get_current_round()}\n")

    # One shared executor to rule them all
    executor = ProcessPoolExecutor()

    # If you have new PDFs, step one is to add them to the list
    if args.add_pdfs:
        assert args.add_pdfs.startswith("s3://"), "PDFs must live on s3"
        
        print(f"Querying all PDFs at {args.add_pdfs}")
        
        all_pdfs = expand_s3_glob(args.add_pdfs)
        print(f"Found {len(all_pdfs)} total pdf paths")

        all_pdfs = [pdf for pdf in all_pdfs if not db.pdf_exists(pdf)]
        print(f"Need to import {len(all_pdfs)} total new pdf paths")

        future_to_path = {executor.submit(get_pdf_num_pages, s3_path): s3_path for s3_path in all_pdfs}
        for future in tqdm(as_completed(future_to_path), total=len(future_to_path)):
            s3_path = future_to_path[future]
            num_pages = future.result()
            if num_pages and not db.pdf_exists(s3_path):
                db.add_pdf(s3_path, num_pages, "pending")

        print("\n")

    # Now build an index of all the pages that were processed within the workspace so far
    print("Indexing all batch inference sent to this workspace")
    inference_output_paths = expand_s3_glob(f"{args.workspace}/inference_outputs/*.jsonl")

    inference_output_paths = [
        (s3_path, etag) for s3_path, etag in inference_output_paths.items()
        if not db.is_file_processed(s3_path, etag)
    ]

    print(f"Found {len(inference_output_paths)} new batch inference results to index")

    future_to_path = {executor.submit(process_jsonl_content, s3_path): (s3_path, etag) for s3_path, etag in inference_output_paths}

    for future in tqdm(as_completed(future_to_path), total=len(future_to_path)):
        s3_path, etag = future_to_path[future]
        inference_records = future.result()

        db.add_index_entries(inference_records)
        db.update_processed_file(s3_path, etag=etag)

    # Now query each pdf, if you have all of the pages needed (all pages present, error is null and finish_reason is stop), then you assemble it into a dolma document and output it
    # If you don't have every page, or if you have pages with errors, then you output a new batch of inference items to use
    future_to_path = {executor.submit(build_pdf_queries, args.workspace, pdf): pdf for pdf in db.get_pdfs_by_status("pending")}
    potentially_done_pdfs = []
    lines_written = 0
    new_inference_writer = BatchWriter(f"{args.workspace}/inference/round_{db.get_current_round()}", args.max_size_mb)

    for future in tqdm(as_completed(future_to_path), total=len(future_to_path)):
        pdf = future_to_path[future]
        inference_lines = future.result()

        if len(inference_lines) == 0:
            potentially_done_pdfs.append(pdf)

        for line in inference_lines:
            lines_written += 1
            new_inference_writer.write_line(json.dumps(line))

    new_inference_writer.close()

    if lines_written > 0:
        db.set_metadata("round", str(db.get_current_round() + 1))

    # Now, finally, assemble any potentially done docs into dolma documents
    future_to_path = {executor.submit(build_dolma_doc, args.workspace, pdf): pdf for pdf in potentially_done_pdfs}
    new_output_writer = BatchWriter(f"{args.workspace}/output", args.max_size_mb)

    for future in tqdm(as_completed(future_to_path), total=len(future_to_path)):
        pdf = future_to_path[future]
        dolma_doc = future.result()

        new_output_writer.write_line(json.dumps(dolma_doc))

    new_output_writer.close()
    
    # TODO
    # 2. Have a way to apply basic spam + language filter if you can during add pdfs step
    # 3. For retrying, make it so you retry several times with different sampling parameters