main.py

import sys

# HOW TO RUN THIS SCRIPT:
# python3 script.py MYFILE.SQL

# TRANSFORM:
# CASE WHEN ('bid_requests' in ({{.METRICS}})) THEN bid_requests ELSE NULL END as bid_requests,
# TO
# {{if index .METRICS_AS_MAP "bid_requests"}}bid_requests,{{end}}
def processMetrics(src: str) -> str:
    out = '{{if index .METRICS_AS_MAP "||KEY||"}}||DATA||{{end}}'

    spaces = src.split("C")[0]

    src = src.replace("CASE WHEN ('", "")

    # Get key
    key = src.split("'")[0].strip()

    # Get data
    src = src.split("THEN")
    src = "THEN".join((src[1:]))
    src = src.replace("ELSE NULL END", "")
    src = src.replace("{{end}}", "")

    out = out.replace("||KEY||", key)
    out = out.replace("||DATA||", src.lstrip().rstrip())

    return spaces + out


# TRANSFORM:
# CASE WHEN 'sitename' in ({{.GROUPBYOPTIONS}}) THEN site_id ELSE null end,
# TO
# {{if index .GROUP_BY_AS_MAP "sitename"}}site_id,{{end}}
def processGroupByOptionsInGroupBy(src: str) -> str:
    out = '{{if index .GROUP_BY_AS_MAP "||KEY||"}}||DATA||{{end}}'

    spaces = src.split("C")[0]

    src = src.replace("CASE WHEN '", "")

    # Get key
    key = src.split("'")[0].strip()

    # Get data
    src = src.split("THEN")
    src = "THEN".join((src[1:]))
    src = src.replace(" ELSE null end", "")
    src = src.replace("{{end}}", "")

    out = out.replace("||KEY||", key)
    out = out.replace("||DATA||", src.lstrip().rstrip())

    return spaces + out


# TRANSFORM:
# {{if .GROUPBYOPTIONS}}CASE WHEN ('biddername' in ({{.GROUPBYOPTIONS}})) THEN bidder_id ELSE NULL END as bidder_id,{{end}}
# TO
# {{if index .GROUP_BY_AS_MAP "biddername"}}bidder_id,{{end}}
def processGroupByOptions(src: str) -> str:
    out = '{{if index .GROUP_BY_AS_MAP "||KEY||"}}||DATA||{{end}}'

    spaces = src.split("{")[0]

    src = src.replace("{{if .GROUPBYOPTIONS}}CASE WHEN ('", "")

    # Get key
    key = src.split("'")[0].strip()

    # Get data
    src = src.split("THEN")
    src = "THEN".join((src[1:]))
    src = src.replace("ELSE NULL END", "")
    src = src.replace("{{end}}", "")

    out = out.replace("||KEY||", key)
    out = out.replace("||DATA||", src.lstrip().rstrip())

    return spaces + out


with open(sys.argv[1]) as f:
    lines = [line.rstrip() for line in f]

out = ""
for l in lines:
    if "{{if .GROUPBYOPTIONS}}CASE WHEN" in l:
        out += processGroupByOptions(l) + "\n"
    elif "in ({{.METRICS}})" in l:
        out += processMetrics(l) + "\n"
    elif "in ({{.GROUPBYOPTIONS}})" in l:
        out += processGroupByOptionsInGroupBy(l) + "\n"
    else:
        out += l + "\n"

print(out)