#!/usr/bin/env python3
"""Phase 0 helper: dump a wasm module's imports, exports, and dylink.0
custom section (memory/table size requirements). Doubles as the reference
for the loader's dylink.0 parsing (§6 step 4)."""
import sys, struct

def uleb(buf, pos):
    result = 0
    shift = 0
    while True:
        b = buf[pos]
        pos += 1
        result |= (b & 0x7f) << shift
        if not (b & 0x80):
            return result, pos
        shift += 7

def name(buf, pos):
    n, pos = uleb(buf, pos)
    return buf[pos:pos+n].decode("utf-8", "replace"), pos + n

def limits(buf, pos):
    flags = buf[pos]; pos += 1
    mn, pos = uleb(buf, pos)
    mx = None
    if flags & 1:
        mx, pos = uleb(buf, pos)
    return (mn, mx), pos

KIND = {0: "func", 1: "table", 2: "memory", 3: "global"}
VALTYPE = {0x7f: "i32", 0x7e: "i64", 0x7d: "f32", 0x7c: "f64", 0x70: "funcref", 0x6f: "externref"}

def main(fn):
    buf = open(fn, "rb").read()
    assert buf[:8] == b"\0asm\x01\0\0\0", "not a wasm module"
    pos = 8
    while pos < len(buf):
        sec_id = buf[pos]; pos += 1
        size, pos = uleb(buf, pos)
        end = pos + size
        if sec_id == 0:
            sname, p = name(buf, pos)
            if sname == "dylink.0":
                print("== dylink.0 ==")
                while p < end:
                    sub = buf[p]; p += 1
                    sublen, p = uleb(buf, p)
                    subend = p + sublen
                    if sub == 1:  # WASM_DYLINK_MEM_INFO
                        memsize, p2 = uleb(buf, p)
                        memalign, p2 = uleb(buf, p2)
                        tabsize, p2 = uleb(buf, p2)
                        tabalign, p2 = uleb(buf, p2)
                        print(f"  mem_info: memsize={memsize} memalign=2^{memalign} tablesize={tabsize} tablealign=2^{tabalign}")
                    else:
                        print(f"  subsection type={sub} len={sublen}")
                    p = subend
            elif sname in ("uce.abi",):
                print(f"== custom section {sname} ({end - p} bytes) ==")
        elif sec_id == 2:
            count, p = uleb(buf, pos)
            print(f"== imports ({count}) ==")
            for _ in range(count):
                mod, p = name(buf, p)
                nm, p = name(buf, p)
                kind = buf[p]; p += 1
                detail = ""
                if kind == 0:
                    _, p = uleb(buf, p)
                elif kind == 1:
                    et = buf[p]; p += 1
                    lim, p = limits(buf, p)
                    detail = f" {VALTYPE.get(et, hex(et))} {lim}"
                elif kind == 2:
                    lim, p = limits(buf, p)
                    detail = f" {lim}"
                elif kind == 3:
                    vt = buf[p]; p += 1
                    mut = buf[p]; p += 1
                    detail = f" {VALTYPE.get(vt, hex(vt))}{' mut' if mut else ''}"
                print(f"  {KIND.get(kind, kind):6} {mod}.{nm}{detail}")
        elif sec_id == 7:
            count, p = uleb(buf, pos)
            print(f"== exports ({count}) ==")
            for _ in range(count):
                nm, p = name(buf, p)
                kind = buf[p]; p += 1
                _, p = uleb(buf, p)
                print(f"  {KIND.get(kind, kind):6} {nm}")
        pos = end

if __name__ == "__main__":
    for fn in sys.argv[1:]:
        print(f"### {fn}")
        main(fn)