from __future__ import annotations
import re, pandas as pd
from pathlib import Path
from .base import *
from .common import DATE_TOKEN_PATTERN, date_iso, find

class IndusIndParser(BaseParser):
    bank_name='IndusInd Bank'; parser_name='IndusIndParser'
    @classmethod
    def detect(cls,text): return 0.98 if 'INDUSIND' in text.upper() and 'STATEMENT OF ACCOUNT' in text.upper() else 0
    def parse(self,path,text=None):
        text=text or extract_text(path); meta=StatementMeta(bank_name=self.bank_name,source_file=Path(path).name,parser_name=self.parser_name,confidence='Medium')
        meta.account_number=find(r'Account Number\s*:\s*([0-9X*]+)',text)
        meta.customer_id=find(r'Cust\.Reln\.No\s*:\s*([0-9X*]+)',text)
        meta.ifsc=find(r'IFSC Code\s*:\s*([A-Z0-9]+)',text)
        m=re.search(rf'Period\s*:\s*({DATE_TOKEN_PATTERN})\s*(?:to|-)\s*({DATE_TOKEN_PATTERN})', text, re.I)
        if m:
            meta.period_from=date_iso(m.group(1)); meta.period_to=date_iso(m.group(2))
        meta.total_debit=amount(find(r'Total Withdrawal Amount\s*:\s*([\d,]+\.\d{2})',text))
        meta.total_credit=amount(find(r'Total Deposit Amount\s*:\s*([\d,]+\.\d{2})',text))
        # rows start with date and often end with amount Dr/Cr and balance Cr
        date_re=re.compile(rf'^\s*({DATE_TOKEN_PATTERN})\s+(.*)$', re.I)
        rows=[]; cur=None; page=1
        for line in text.splitlines():
            if '\f' in line: page+=line.count('\f')
            m=date_re.match(line)
            if m:
                if cur: rows.append(cur)
                cur={'transaction_date':m.group(1),'value_date':m.group(1),'lines':[m.group(2)],'source_page':page}
            elif cur and line.strip() and not re.match(r'^(Statement Summary|Opening Balance|Total Withdrawal|Branch Address|The limits)',line.strip(),re.I): cur['lines'].append(line)
        if cur: rows.append(cur)
        out=[]; prev=None
        for r in rows:
            first=r['lines'][0]; alltxt=norm(' '.join(r['lines']))
            # Typical: narration ref debit Dr credit Cr balance Cr
            tokens=list(re.finditer(r'([\d,]+\.\d{2})\s*(Dr|Cr)',first,re.I))
            if not tokens: continue
            debit=credit=bal=None
            if len(tokens)>=2:
                bal=amount(tokens[-1].group(1))
                txn=amount(tokens[-2].group(1)); typ=tokens[-2].group(2).upper()
                if typ=='DR': debit=txn
                else: credit=txn
            elif len(tokens)==1:
                # carried forward / balance-only line; skip
                continue
            narr=first[:tokens[-2].start()].strip()+' '+' '.join(x.strip() for x in r['lines'][1:])
            ref=''; z=re.search(r'\b([A-Z0-9]{8,})\b',narr); ref=z.group(1) if z else ''
            out.append({**r,'narration':norm(narr),'reference_no':ref,'debit':debit,'credit':credit,'balance':bal})
        if out:
            f=out[0]; meta.opening_balance=round((f['balance'] or 0)+(f.get('debit') or 0)-(f.get('credit') or 0),2)
            meta.closing_balance=out[-1]['balance']
        return meta,finalize(pd.DataFrame(out),meta)