#!/usr/bin/env python3
"""Generate the four embeddable charts for field study No. 05 (Charleston
Tri-County, SC).

Every plotted value is READ FROM charleston-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_charleston.py,
published beside it.

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

Same drawing code as the Harris and Mecklenburg studies, so the five 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, "charleston-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)

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})")



BUCKETS = ["Sold before 2012", "Sold 2012-2014", "Sold 2015-2017",
           "Sold 2018-2021", "Sold 2022-2025"]
SHORT = {"Sold before 2012": "before 2012", "Sold 2012-2014": "2012-14",
         "Sold 2015-2017": "2015-17", "Sold 2018-2021": "2018-21",
         "Sold 2022-2025": "2022-25"}

# --- Finding 01: the gradient -------------------------------------------------
rows = []
for county, label, hot in (("Berkeley commercial", "Berkeley", True),
                           ("Dorchester 6% class", "Dorchester", False)):
    for b in BUCKETS:
        rows.append((f"{label}, sold {SHORT[b].replace('before ', 'before ')}",
                     num(f"{county} / {b} / median gap below market"), hot))

chart("field-study-05-reset-gradient.svg",
      "What a commercial property is taxed on depends on when it last sold",
      "Median shortfall of taxable value below the county's own market value, "
      "by the year the property last changed hands",
      rows, 60, [0, 15, 30, 45, 60],
      [(ACCENT, "Berkeley County, parcels with a commercial building (n=3,357)"),
       (GRAY, "Dorchester County, the 6% assessment class (n=26,182)")],
      "South Carolina resets a property's taxable value when it changes hands. "
      "Two counties, two unrelated CAMA vendors, the same gradient. Counted "
      "20 September 2026 from each county's own public parcel service.",
      fmt="{:.1f}%", tickfmt="{}%")

# --- Finding 01b: how many show any gap at all --------------------------------
rows = []
for county, label, hot in (("Berkeley commercial", "Berkeley", True),
                           ("Dorchester 6% class", "Dorchester", False)):
    for b in BUCKETS:
        rows.append((f"{label}, sold {SHORT[b]}",
                     num(f"{county} / {b} / share showing any gap"), hot))

chart("field-study-05-any-gap.svg",
      "The longer it has been held, the likelier it is taxed below market",
      "Share of commercial parcels whose taxable value sits more than 1% below "
      "market value",
      rows, 100, [0, 25, 50, 75, 100],
      [(ACCENT, "Berkeley County, parcels with a commercial building"),
       (GRAY, "Dorchester County, the 6% assessment class")],
      "Even among the most recently sold, some gap remains: a sale is not the "
      "only thing that can reset a value, and not every transfer is an "
      "assessable transfer of interest. Counted 20 September 2026.",
      fmt="{:.1f}%", tickfmt="{}%")

# --- Finding 03: the column Charleston does not have --------------------------
chart("field-study-05-charleston-blank.svg",
      "The biggest county in the metro cannot show this at all",
      "Charleston County parcels carrying each value, of 197,620 in the "
      "county's public parcel layer",
      [("Appraised (market) value",
        num("Charleston parcels carrying an appraised (market) value"), False),
       ("Taxable or assessed value",
        num("Charleston parcels carrying a taxable or assessed value"), True)],
      200000, [0, 50000, 100000, 150000, 200000],
      [(GRAY, "Published by Charleston County"),
       (ACCENT, "Not present in any of the layer's 47 columns")],
      "The gap between taxable and market value can only be measured where "
      "both are published. Charleston County publishes one of them. Counted "
      "20 September 2026.",
      fmt="{:,}", tickfmt="{:,}")

# --- Finding 04: an undocumented code set -------------------------------------
codes = sorted(((k.split()[3], num(k)) for k in V
                if k.startswith("Berkeley Validity code ")
                and not k.startswith("Berkeley Validity code (blank)")),
               key=lambda kv: -kv[1])[:10]
chart("field-study-05-validity.svg",
      "The metro's only sale-qualification field, and no published legend",
      "Rows carrying each Validity code on Berkeley County's 123,050-parcel "
      "roll, ten most common",
      [(f"Code {c}", n, c in ("0", "0A")) for c, n in codes],
      max(n for _, n in codes), [0, 15000, 30000, 45000, 60000],
      [(ACCENT, "Codes 0 and 0A, which behave like arm's-length in the data"),
       (GRAY, "Codes whose meaning the county does not publish")],
      "Every field in the service returns a null domain, the subtype list is "
      "empty, and no county or vendor document defines these codes. We count "
      "them; we do not name them. Counted 20 September 2026.",
      fmt="{:,}", tickfmt="{:,}")