#!/usr/bin/env python3
"""Generate the four embeddable charts for field study No. 06 (Nashville /
Davidson County, TN).

Every plotted value is READ FROM nashville-commercial-record-2026-09.csv at run
time. Nothing is typed in by hand: if a metric is not in the CSV, this script
raises rather than draw it. The CSV is produced by count_nashville.py,
published beside it.

    python3 make-charts.py [path/to/nashville-commercial-record-2026-09.csv]

Same drawing code as studies No. 03, 04 and 05, so the six studies share one
visual language."""

import csv, os, sys

HERE = os.path.dirname(os.path.abspath(__file__))
CSV_PATH = sys.argv[1] if len(sys.argv) > 1 else os.path.join(
    HERE, "nashville-commercial-record-2026-09.csv")

def load(path):
    vals = {}
    with open(path, newline="", encoding="utf-8") as fh:
        rows = [ln for ln in fh if not ln.startswith("#")]
    for r in csv.DictReader(rows):
        vals[r["metric"]] = (r["value"], r["share"])
    if not vals:
        raise SystemExit("no metrics parsed from " + path)
    return vals

V = load(CSV_PATH)

def num(metric):
    """A figure, straight from the CSV. KeyError if it was never counted."""
    if metric not in V:
        raise KeyError("not in the CSV, so it was not counted: " + metric)
    s = V[metric][0]
    return float(s) if "." in s else int(s)

def share(metric):
    """The share as the CSV prints it, as a number. Never recomputed here."""
    if metric not in V or not V[metric][1]:
        raise KeyError("no share in the CSV for: " + metric)
    return float(V[metric][1].rstrip("%"))

SURFACE="#f7f5ed"; INK="#173e32"; MUTED="#7b9384"
ACCENT="#0d6b47"; GRAY="#b6c4b5"; GRID="#d9e0d4"
FONT="system-ui,-apple-system,'Segoe UI',Helvetica,Arial,sans-serif"
CREDIT="Sterling Digital Partners · glvtl.com/field-study"

def bar(x,y,w,h,r=4):
    if w<=r: return f'<rect x="{x}" y="{y}" width="{max(w,1):.1f}" height="{h}" fill="currentColor"/>'
    return (f'<path d="M{x},{y} H{x+w-r:.1f} A{r},{r} 0 0 1 {x+w:.1f},{y+r} '
            f'V{y+h-r} A{r},{r} 0 0 1 {x+w-r:.1f},{y+h} H{x} Z" fill="currentColor"/>')

def wrap(t,n=112):
    out,cur=[],""
    for w in t.split():
        if len(cur)+len(w)+1>n: out.append(cur); cur=w
        else: cur=(cur+" "+w).strip()
    if cur: out.append(cur)
    return out

def chart(fn,title,sub,rows,axis_max,ticks,legend,note,W=720,L=248,fmt="{:,}",tickfmt=None):
    n=len(rows); band=38; top=92
    tickfmt = tickfmt or fmt
    nl=wrap(note)
    H=top+n*band+34+len(legend)*19+len(nl)*16+32
    R=66; pw=W-L-R
    s=[f'<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 {W} {H}" width="{W}" height="{H}" '
       f'role="img" aria-label="{title}. {sub}" font-family="{FONT}">',
       f'<title>{title}</title><desc>{sub} {note}</desc>',
       f'<rect width="{W}" height="{H}" fill="{SURFACE}"/>',
       f'<text x="0" y="30" font-size="19" font-weight="600" fill="{INK}">{title}</text>',
       f'<text x="0" y="54" font-size="13.5" fill="{MUTED}">{sub}</text>']
    for t in ticks:
        x=L+pw*t/axis_max
        s.append(f'<line x1="{x:.1f}" y1="{top-12}" x2="{x:.1f}" y2="{top+n*band-10}" stroke="{GRID}" stroke-width="1"/>')
        s.append(f'<text x="{x:.1f}" y="{top+n*band+8}" font-size="11.5" fill="{MUTED}" text-anchor="middle">{tickfmt.format(t)}</text>')
    for i,(lab,val,hot) in enumerate(rows):
        y=top+i*band; w=pw*val/axis_max; c=ACCENT if hot else GRAY
        s.append(f'<text x="{L-14}" y="{y+14}" font-size="13" fill="{INK}" text-anchor="end">{lab}</text>')
        s.append(f'<g color="{c}">{bar(L,y,w,20)}</g>')
        s.append(f'<text x="{L+w+9:.1f}" y="{y+14}" font-size="13" font-weight="600" fill="{INK}">{fmt.format(val)}</text>')
    ly=top+n*band+32
    for j,(sw,txt) in enumerate(legend):
        yy=ly+j*19
        s.append(f'<rect x="0" y="{yy-9}" width="11" height="11" rx="2" fill="{sw}"/>')
        s.append(f'<text x="18" y="{yy}" font-size="12.5" fill="{MUTED}">{txt}</text>')
    ny=ly+len(legend)*19+10
    for k,line in enumerate(nl):
        s.append(f'<text x="0" y="{ny+k*16}" font-size="11.5" fill="{MUTED}">{line}</text>')
    s.append(f'<text x="{W}" y="{H-9}" font-size="11.5" font-weight="600" fill="{ACCENT}" '
             f'text-anchor="end">{CREDIT}</text>')
    s.append('</svg>')
    open(os.path.join(HERE,fn),'w').write('\n'.join(s))
    print("wrote",fn,f"({W}x{H})")

def stacked(fn,title,sub,rows,legend,note,W=720,L=206):
    nl=wrap(note); band=54; top=98
    H=top+len(rows)*band+18+len(legend)*19+len(nl)*16+32
    R=26; pw=W-L-R
    s=[f'<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 {W} {H}" width="{W}" height="{H}" '
       f'role="img" aria-label="{title}. {sub}" font-family="{FONT}">',
       f'<title>{title}</title><desc>{sub} {note}</desc>',
       f'<rect width="{W}" height="{H}" fill="{SURFACE}"/>',
       f'<text x="0" y="30" font-size="19" font-weight="600" fill="{INK}">{title}</text>',
       f'<text x="0" y="54" font-size="13.5" fill="{MUTED}">{sub}</text>']
    for i,(lab,a,b,ntxt) in enumerate(rows):
        y=top+i*band; tot=a+b
        wa=pw*a/tot; wb=pw*b/tot-2
        s.append(f'<text x="{L-14}" y="{y+13}" font-size="13.5" fill="{INK}" text-anchor="end">{lab}</text>')
        s.append(f'<text x="{L-14}" y="{y+31}" font-size="12" fill="{MUTED}" text-anchor="end">{ntxt}</text>')
        s.append(f'<g color="{ACCENT}">{bar(L,y,wa,24,0)}</g>')
        s.append(f'<g color="{GRAY}">{bar(L+wa+2,y,wb,24)}</g>')
        s.append(f'<text x="{L+10}" y="{y+16.5}" font-size="13" font-weight="600" fill="#f7f5ed">'
                 f'{a*100.0/tot:.1f}%</text>')
        s.append(f'<text x="{L+wa+12}" y="{y+16.5}" font-size="13" font-weight="600" fill="{INK}">'
                 f'{b*100.0/tot:.1f}%</text>')
    ly=top+len(rows)*band+6
    for j,(sw,txt) in enumerate(legend):
        yy=ly+j*19
        s.append(f'<rect x="0" y="{yy-9}" width="11" height="11" rx="2" fill="{sw}"/>')
        s.append(f'<text x="18" y="{yy}" font-size="12.5" fill="{MUTED}">{txt}</text>')
    ny=ly+len(legend)*19+10
    for k,line in enumerate(nl):
        s.append(f'<text x="0" y="{ny+k*16}" font-size="11.5" fill="{MUTED}">{line}</text>')
    s.append(f'<text x="{W}" y="{H-9}" font-size="11.5" font-weight="600" fill="{ACCENT}" '
             f'text-anchor="end">{CREDIT}</text>')
    s.append('</svg>')
    open(os.path.join(HERE,fn),'w').write('\n'.join(s))
    print("wrote",fn,f"({W}x{H})")



# --- Finding 01: the address is not the government ---------------------------
CITIES = ["Berry Hill", "Belle Meade", "Oak Hill", "Forest Hills",
          "Goodlettsville", "Ridgetop"]
rows = []
for c in CITIES:
    pc = share(f"{c} parcels with a NASHVILLE property address")
    rows.append((f"{c} ({num(c + ' parcels'):,} parcels)", pc, pc > 99))
chart("field-study-06-satellite-cities.svg",
      "Six cities inside Davidson County. Four of them are addressed Nashville",
      "Share of each separately incorporated city's parcels whose property "
      "address reads NASHVILLE",
      rows, 100, [0, 25, 50, 75, 100],
      [(ACCENT, "Every parcel in the city carries a Nashville address"),
       (GRAY, "Some or none do")],
      "Berry Hill and Belle Meade return exactly one distinct property-city "
      "value between them, and it is NASHVILLE. Counted 20 September 2026 from "
      "Metro Nashville's own parcel service.",
      fmt="{:.1f}%", tickfmt="{}%")

# --- Finding 02: the whitespace that hides a district -------------------------
rows = []
for code, label in [("USD", "Urban Services District"),
                    ("GSD", "General Services District"),
                    ("GO", "Goodlettsville"), ("BH", "Berry Hill"),
                    ("FH", "Forest Hills"), ("OH", "Oak Hill")]:
    k = f"TaxDist {code} parcels missed by an exact match"
    rows.append((f"{label} ({code})", num(k), code in ("USD", "GSD")))
chart("field-study-06-whitespace.svg",
      "43,132 parcels are invisible to an exact-match filter",
      "Parcels whose tax district is stored with trailing whitespace, and so "
      "are missed by a query for the district's own code",
      rows, 40000, [0, 10000, 20000, 30000, 40000],
      [(ACCENT, "Metro Nashville's own service districts"),
       (GRAY, "Separately incorporated cities")],
      "The column holds 22 distinct values. There are 15 districts. Nothing "
      "errors; the rows simply do not come back. Counted 20 September 2026.",
      fmt="{:,}", tickfmt="{:,}")

# --- Finding 04: one code, two classifications --------------------------------
SPLITS = [("012", "DUPLEX"), ("015", "RESIDENTIAL CONDO"),
          ("020", "VACANT COMMERCIAL LAND"), ("016", "ZERO LOT LINE"),
          ("010", "VACANT RESIDENTIAL LAND"), ("011", "SINGLE FAMILY")]
rows = []
for code, desc in SPLITS:
    k = f"Code {code} ({desc}) assessed at 40%"
    rows.append((f"{code} {desc.title()}", share(k), code in ("012", "011")))
chart("field-study-06-classification.svg",
      "The same land use code, assessed under two different classifications",
      "Share of each code's parcels assessed at Tennessee's 40% commercial "
      "and industrial ratio; the rest are at 25% or zero",
      rows, 100, [0, 25, 50, 75, 100],
      [(ACCENT, "Codes whose own description reads as residential"),
       (GRAY, "Other codes split across both ratios")],
      "Tennessee assesses commercial and industrial real property at 40% of "
      "appraised value and residential and farm property at 25%. Seven codes "
      "carry parcels on both sides. Counted 20 September 2026.",
      fmt="{:.1f}%", tickfmt="{}%")

# --- Finding 06: what the sale record carries ---------------------------------
comm = num("Parcels classified commercial or industrial by the assessor")
noprice = num("Commercial parcels carrying no sale price at all")
priced = num("Commercial parcels carrying a sale price")
stacked("field-study-06-sale-record.svg",
        "Two in five commercial parcels carry no sale price at all",
        "Davidson County parcels the assessor classifies commercial or "
        "industrial, by whether the record carries a price",
        [("Commercial parcels", noprice, priced,
          f"{comm:,} parcels assessed at 40%")],
        [(ACCENT, "No sale price in the record"),
         (GRAY, "A sale price, under one of 28 undocumented codes")],
        "The field named ValidSale is populated on 4 of the county's 287,112 "
        "parcels. Counted 20 September 2026.")