from bs4 import BeautifulSoup
import pandas as pd
import requests

# Pull the latest pages of https://www.finance-ni.gov.uk/publications/ni-house-price-index-statistical-reports and extract links

base_url= 'https://www.finance-ni.gov.uk/publications/ni-house-price-index-statistical-reports'
base_content = requests.get(base_url).content
base_soup = BeautifulSoup(base_content)

for a in base_soup.find_all('a'):
    if a.attrs.get('href','').endswith('xlsx'):
        source_name, source_url = a.contents[1],a.attrs['href']
        
source_df = pd.read_excel(source_url, sheet_name = None) # Load all worksheets in 

source_df.keys()

source_df['Contents']

new_header = source_df['Contents'].iloc[0]
source_df['Contents'] = source_df['Contents'][1:]
source_df['Contents'].columns = new_header

source_df['Contents'].columns = [*new_header[:-1],'Title']

[t for t in source_df['Contents']['Title'].values if t.startswith('Table')]

# Replace 'Figure' with 'Fig' in 'Worksheet Name'
with pd.option_context('mode.chained_assignment',None):
    source_df['Contents']['Worksheet Name'] = source_df['Contents']['Worksheet Name'].str.replace('Figure','Fig')

source_df['Table 1']

def basic_cleanup(df:pd.DataFrame, offset=1)->pd.DataFrame:
    df = df.copy() 
    # Re-header from row 1 (which was row 3 in excel)
    new_header = df.iloc[offset]
    df = df.iloc[offset+1:]
    df.columns = new_header
    
    # remove 'NaN' trailing columns
    df = df[df.columns[pd.notna(df.columns)]]
    
    # 'NI' is a usually hidden column that appears to be a checksum; 
    #if it's all there and all 100, remove it, otherwise, complain.
    # (Note, need to change this 'if' logic to just 'if there's a 
    # column with all 100's, but cross that bridge later)
    if 'NI' in df:
        assert df['NI'].all() and df['NI'].mean() == 100, "Not all values in df['NI'] == 100"
        df = df.drop('NI', axis=1)
        
    # Strip rows below the first all-nan row, if there is one 
    # (Otherwise this truncates the tables as there is no
    # idxmax in the table of all 'false's)
    if any(df.isna().all(axis=1)):
        idx_first_bad_row = df.isna().all(axis=1).idxmax()
        df = df.loc[:idx_first_bad_row-1]
    
    # By Inspection, other tables use 'Sale Year' and 'Sale Quarter'
    if set(df.keys()).issuperset({'Sale Year','Sale Quarter'}):
        df = df.rename(columns = {
            'Sale Year':'Year',
            'Sale Quarter': 'Quarter'
        })
        
    # For 'Year','Quarter' indexed pages, there is an implied Year
    # in Q2/4, so fill it downwards
    if set(df.keys()).issuperset({'Year','Quarter'}):
        df['Year'] = df['Year'].astype(float).fillna(method='ffill').astype(int)
        
        # In Pandas we can represent Y/Q combinations as proper datetimes
        #https://stackoverflow.com/questions/53898482/clean-way-to-convert-quarterly-periods-to-datetime-in-pandas 
        df.insert(loc=0,
                  column='Period',
                  value=pd.PeriodIndex(df.apply(lambda r:f'{r.Year}-{r.Quarter}', axis=1), freq='Q')
        )
    
    # reset index, try to fix dtypes, etc, (this should be the last 
    # operation before returning!
    df = df.reset_index(drop=True).infer_objects()   
    
    return df

df = basic_cleanup(source_df['Table 1'])
df

dest_df = {
    'Table 1': basic_cleanup(source_df['Table 1'])
}

len([k for k in source_df.keys() if k.startswith('Table')])

df = basic_cleanup(source_df['Table 2'])
df

df.columns = [c.split('\n')[0] for c in df.columns]
df

dest_df['Table 2'] = df

df = basic_cleanup(source_df['Table 2a'])
df

dest_df['Table 2']['Property Type']

import re

table2s = re.compile('Table 2[a-z]')
assert table2s.match('Table 2') is None, 'Table 2 is matching itself!'
assert table2s.match('Table 20') is None, 'Table 2 is greedy!'
assert table2s.match('Table 2z') is not None, 'Table 2 is matching incorrectly!'

table2s = re.compile('Table 2[a-z]')
for table in source_df:
    if table2s.match(table):
        dest_df[table] = basic_cleanup(source_df[table])

len(dest_df), len([k for k in source_df.keys() if k.startswith('Table') and k not in dest_df])

df = basic_cleanup(source_df['Table 3'])
df.columns = [c.split('\n')[0] for c in df.columns] # Stolen from Table 2 Treatment
df

dest_df['Table 3'] = df

df = basic_cleanup(source_df['Table 3a'])
df

table3s = re.compile('Table 3[a-z]')
for table in source_df:
    if table3s.match(table):
        dest_df[table] = basic_cleanup(source_df[table])
len(dest_df), len([k for k in source_df.keys() if k.startswith('Table') and k not in dest_df])

df = source_df['Table 4']
df

df.iloc[:,1]=df.iloc[:,1].str.replace('Quarter ([1-4])',r'Q\1', regex=True)
df

df=df[~df.iloc[:,1].str.contains('Total').fillna(False)]

# Lose the year new-lines (needs astype because non str lines are
# correctly inferred to be ints, so .str methods nan-out
with pd.option_context('mode.chained_assignment',None):
    df.iloc[:,0]=df.iloc[:,0].astype(str).str.replace('\n','') 

df

basic_cleanup(df, offset=3)

def cleanup_table_4(df):
    """
    Table 4: Number of Verified Residential Property Sales
    * Regex 'Quarter X' to 'QX' in future 'Sales Quarter' column
    * Drop Year Total rows
    * Clear any Newlines from the future 'Sales Year' column
    * call `basic_cleanup` with offset=3
    """
    df.iloc[:,1]=df.iloc[:,1].str.replace('Quarter ([1-4])',r'Q\1', regex=True)
    df=df[~df.iloc[:,1].str.contains('Total').fillna(False)]
    # Lose the year new-lines (needs astype because non str lines are
    # correctly inferred to be ints, so .str methods nan-out
    with pd.option_context('mode.chained_assignment',None):
        df.iloc[:,0]=df.iloc[:,0].astype(str).str.replace('\n','') 
    return basic_cleanup(df, offset=3)

cleanup_table_4(source_df['Table 4'].copy())

dest_df['Table 4'] = cleanup_table_4(source_df['Table 4'])
len(dest_df), len([k for k in source_df.keys() if k.startswith('Table') and k not in dest_df])

df = basic_cleanup(source_df['Table 5'])
df

# Two inner-columns per LGD
lgds = df.columns[3:].str.replace(' HPI','').str.replace(' Standardised Price','').unique()
lgds

lgds = df.columns[3:].str.replace(' Standardised HPI',' HPI')\
    .str.replace(' HPI','')\
    .str.replace(' Standardised Price','').unique()
lgds

df.columns = [*df.columns[:3], *pd.MultiIndex.from_product([lgds,['Index','Price']], names=['LGD','Metric'])]
df

def cleanup_table_5(df):
    """
    Table 5: Standardised House Price & Index for each Local Government District Northern Ireland
    * 
    """
    # Basic Cleanup first
    df = basic_cleanup(df)
    # Build multi-index of LGD / Metric [Index,Price]
    # Two inner-columns per LGD
    lgds = df.columns[3:].str.replace(' Standardised HPI',' HPI')\
        .str.replace(' HPI','')\
        .str.replace(' Standardised Price','')\
        .unique()
    df.columns = [*df.columns[:3], *pd.MultiIndex.from_product([lgds,['Index','Price']], names=['LGD','Metric'])]
    return df

cleanup_table_5(source_df['Table 5'])

dest_df['Table 5']=cleanup_table_5(source_df['Table 5'])
len(dest_df), len([k for k in source_df.keys() if k.startswith('Table') and k not in dest_df])

df = source_df['Table 5a'].copy()
df

dates = df.iloc[:,0].str.extract('(Q[1-4]) ([0-9]{4})').rename(columns={0:'Quarter',1:'Year'})
for c in ['Quarter','Year']:# insert the dates in order, so they come out in reverse in the insert
    df.insert(1,c,dates[c])
    df.iloc[2,1]=c # Need to have the right colname for when `basic_cleanup` is called.

df.iloc[2,1]=c
df

df=df[~df.iloc[:,0].str.contains('Total').fillna(False)]

basic_cleanup(df,offset=2)

def cleanup_table_5a(df):
    """
    Table 5a: Number of Verified Residential Property Sales by Local Government District
    * Parse the 'Sale Year/Quarter' to two separate cols
    * Insert future-headers for Quarter and Year cols
    * Remove rows with 'total' in the first column
    * Disregard the 'Sale Year/Quarter' column
    * perform `basic_cleanup` with offset=2
    """
    # Safety first
    df=df.copy()
    
    # Extract 'Quarter' and 'Year' columns from the future 'Sale Year/Quarter' column
    dates = df.iloc[:,0].str.extract('(Q[1-4]) ([0-9]{4})').rename(columns={0:'Quarter',1:'Year'})
    for c in ['Quarter','Year']:# insert the dates in order, so they come out in reverse in the insert
        df.insert(1,c,dates[c])
        df.iloc[2,1]=c # Need to have the right colname for when `basic_cleanup` is called.

    # Remove 'total' rows from the future 'Sale Year/Quarter' column
    df=df[~df.iloc[:,0].str.contains('Total').fillna(False)]
    
    # Remove the 'Sale Year/Quarter' column all together
    df = df.iloc[:,1:]
    
    # Standard cleanup
    df = basic_cleanup(df, offset=2)
    
    return df

cleanup_table_5a(source_df['Table 5a'])

dest_df['Table 5a']=cleanup_table_5a(source_df['Table 5a'])
len(dest_df), len([k for k in source_df.keys() if k.startswith('Table') and k not in dest_df])

df = basic_cleanup(source_df['Table 6'])
df

dest_df['Table 6']=basic_cleanup(source_df['Table 6'])
len(dest_df), len([k for k in source_df.keys() if k.startswith('Table') and k not in dest_df])

df = source_df['Table 7'].copy()
df.head()

df.iloc[1,0] = 'Year'
df.iloc[1,1] = 'Quarter'
df.head()

basic_cleanup(df).head()

def cleanup_table_7(df):
    """
    Table 7: Standardised House Price & Index for Rural Areas of Northern Ireland by drive times
    * Insert Year/Quarter future-headers
    * Clean normally
    # TODO THIS MIGHT BE VALID FOR MULTIINDEXING ON DRIVETIME/[Index/Price]
    """
    df = df.copy()
    df.iloc[1,0] = 'Year'
    df.iloc[1,1] = 'Quarter'
    df = basic_cleanup(df)
    return df

cleanup_table_7(source_df['Table 7'])

dest_df['Table 7'] = cleanup_table_7(source_df['Table 7'])
len(dest_df), len([k for k in source_df.keys() if k.startswith('Table') and k not in dest_df])

cleanup_table_5a(source_df['Table 8']).head()

cleanup_table_8 = cleanup_table_5a

dest_df['Table 8'] = cleanup_table_8(source_df['Table 8'])
len(dest_df), len([k for k in source_df.keys() if k.startswith('Table') and k not in dest_df])

basic_cleanup(source_df['Table 9'])

dest_df['Table 9'] = basic_cleanup(source_df['Table 9'])
len(dest_df), len([k for k in source_df.keys() if k.startswith('Table') and k not in dest_df])

cleanup_table_7(source_df['Table 9a'])

cleanup_table_9x = cleanup_table_7

table9s = re.compile('Table 9[a-z]')
for table in source_df:
    if table9s.match(table):
        dest_df[table] = cleanup_table_9x(source_df[table])
len(dest_df), len([k for k in source_df.keys() if k.startswith('Table') and k not in dest_df])

source_df['Table 10a']

cleanup_table_5a(source_df['Table 10a'])

cleanup_table_10x = cleanup_table_5a

table10s = re.compile('Table 10[a-z]')
for table in source_df:
    if table10s.match(table):
        dest_df[table] = cleanup_table_10x(source_df[table])
len(dest_df), len([k for k in source_df.keys() if k.startswith('Table') and k not in dest_df])

dest_df['Contents'] = source_df['Contents'][source_df['Contents']['Worksheet Name'].str.startswith('Table')]

with pd.ExcelWriter('NI Housing Price Index.xlsx') as writer:
    # Thankfully these are semantically sortable otherwise this would be a _massive_ pain
    for k,df in sorted(dest_df.items()):
        df.to_excel(writer, sheet_name=k)