/*
 * wwi.c — `.wwi` export-data producer (w6c -I): a re-parseable ww-prototype
 * rendering of a package's exported surface and compiler-private closure.
 * Since the sep-compile flip
 * (epic #22) this is the LIVE import path — the driver runs one `w6c -c -I`
 * per package and feeds each dep's `.wwi` to its importers through a separate
 * canonical `--import` input; the combined.ww amalgamator is gone.
 *
 * Specs: .ai/rob-M2-spec.md (producer) + .ai/drew-M2-checkexported.md
 * (check_exported_type). Two load-bearing choices follow them:
 *
 *   - Unparse walks the AST type-expr subtree (the N_T* nodes), NOT the
 *     checked Type* — tinfo collapses nominal pkg.Name identity (MEMORY
 *     tinfo_lossy_nominal). The AST preserves surface syntax + names.
 *   - Reachable owner-private nominal types are encoded without `export`.
 *     They let a consumer reconstruct public signatures without making the
 *     private spelling source-importable.
 *
 * A `.wwi` is ONE package's self-contained interface. The primary section
 * is followed by compiler-owned `//ww:module <path>` sections for exported
 * foreign type/const facts recursively needed by the public surface. The
 * package driver therefore only needs to pass a package's DIRECT imports;
 * the interface itself carries the selected public type closure. Output is
 * a pure function of the exported API: byte-sorted imports, declarations,
 * fact owners and fact names (no map/hash iteration order).
 */
#include "gc.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

static int
wwi_primary(Node *n)
{
	/* imported == 1 marks a decl reached through a `//ww:module <path>`
	 * boundary (an imported module's concatenated section). */
	return n && n->imported == 0;
}

/* check_exported_type (drew): resolve an N_TNAME to its type sym WITHOUT
 * the side effects of resolve_typename (no on-demand resolve, no double
 * "unknown type" error). A primitive/keyword resolves to no SK_TYPE →
 * leaf. By the time the producer runs, check_file has finished and
 * c->cur == c->top.
 */
static int
wwi_mod_eq(const char *a, const char *b)
{
	if (a == NULL || b == NULL) return a == b;
	return strcmp(a, b) == 0;
}

/* The import alias map is source-owner-local. Imported `.wwi` sections are
 * flat in the parser, so consulting every N_USE without this owner filter
 * would let one dependency accidentally resolve another dependency's alias. */
static const char *
wwi_use_path(Checker *c, const char *owner, int source, const char *alias)
{
	for (Node *u = c->file->list; u; u = u->next) {
		if (u->kind != N_USE || u->str == NULL
		    || u->sourceid != source || strcmp(u->str, alias) != 0)
			continue;
		int same = owner == NULL ? u->imported == 0
		    : u->imported != 0 && wwi_mod_eq(u->module, owner);
		if (same)
			return u->usepath ? u->usepath : u->str;
	}
	return NULL;
}

static int
wwi_direct_mod_visible(Checker *c, const char *owner, int source,
    const char *mod)
{
	if (mod == NULL || mod[0] == '\0') return 0;
	for (Node *u = c->file->list; u; u = u->next) {
		if (u->kind != N_USE || u->sourceid != source) continue;
		int same = owner == NULL ? u->imported == 0
		    : u->imported != 0 && wwi_mod_eq(u->module, owner);
		const char *path = u->usepath ? u->usepath : u->str;
		if (same && path != NULL && strcmp(path, mod) == 0) return 1;
	}
	return 0;
}

static Sym *
wwi_typesym(Checker *c, const char *owner, int source, const char *nm)
{
	if (nm == NULL) return NULL;
	const char *dot = strrchr(nm, '.');
	Sym *s = NULL;
	if (dot) {
		size_t n = (size_t)(dot - nm);
		char *alias = malloc(n + 1);
		if (alias == NULL) fatal("wwi: out of memory");
		memcpy(alias, nm, n);
		alias[n] = '\0';
		const char *mod = wwi_use_path(c, owner, source, alias);
		if (mod)
			s = scope_lookup_in_module(c->cur, mod, dot + 1);
		free(alias);
	} else {
		s = scope_lookup_type(c->cur, owner, nm);
		if (s == NULL) {
			for (Scope *p = c->cur; p; p = p->parent) {
				for (Sym *b = p->first; b; b = b->next) {
					if (b->kind == SK_TYPE
					    && strcmp(b->name, nm) == 0
					    && wwi_direct_mod_visible(c, owner, source,
					        b->mod)) {
						s = b;
						break;
					}
				}
				if (s != NULL) break;
			}
		}
	}
	if (s && s->kind == SK_TYPE)
		return s;
	return NULL;
}

static int
wwi_check_type(Checker *c, const char *owner, Pos loc, Node *t)
{
	int bad = 0;
	if (t == NULL)
		return 0;
	switch (t->kind) {
	case N_TNAME: {
		/* Nominal references, including private ones, are collected into
		 * the self-contained fact closure below. */
		break;
	}
	case N_TPTR:
	case N_TSLICE:
	case N_TBANG:
	case N_TCHAN:
		bad |= wwi_check_type(c, owner, loc, t->lhs);
		break;
	case N_TARRAY:
		/* element only; the length is a const-expr, not a type. */
		bad |= wwi_check_type(c, owner, loc, t->lhs);
		break;
	case N_TFN:
		for (Node *p = t->list; p; p = p->next)
			bad |= wwi_check_type(c, owner, loc, p->lhs);
		bad |= wwi_check_type(c, owner, loc, t->lhs);
		break;
	case N_TSTRUCT:
		for (Node *f = t->list; f; f = f->next)
			bad |= wwi_check_type(c, owner, loc, f->lhs);
		break;
	case N_TTAGGED:
	case N_TTUPLE:
		for (Node *e = t->list; e; e = e->next)
			bad |= wwi_check_type(c, owner, loc, e);
		break;
	case N_TENUM:
		/* the inline enum body is the definition, not a reference;
		 * recurse only its storage type (members are values). */
		bad |= wwi_check_type(c, owner, loc, t->lhs);
		break;
	default:
		/* a non-type node in type position should not occur — leaf. */
		break;
	}
	return bad;
}

static int
wwi_check_decl(Checker *c, Node *d)
{
	int bad = 0;
	switch (d->kind) {
	case N_FNDECL:
		for (Node *p = d->list; p; p = p->next)
			bad |= wwi_check_type(c, NULL, d->pos, p->lhs);
		bad |= wwi_check_type(c, NULL, d->pos, d->lhs);	/* ret */
		break;
	case N_TYPEDECL:
		bad |= wwi_check_type(c, NULL, d->pos, d->lhs);
		break;
	case N_DEF:
		/* the declared type; the rhs const value is not a type. */
		bad |= wwi_check_type(c, NULL, d->pos, d->lhs);
		break;
	case N_LET:
		bad |= wwi_check_type(c, NULL, d->pos, d->lhs);
		break;
	default:
		break;
	}
	return bad;
}

/* type-expr unparse per rob §2.2; const-expr per rob §2.4. */

static void wwi_expr(FILE *of, Node *e);
static void wwi_type(FILE *of, Node *t);

static void
wwi_quote(FILE *of, const char *s, u64 n)
{
	fputc('"', of);
	for (u64 i = 0; i < n; i++) {
		unsigned char c = (unsigned char)s[i];
		switch (c) {
		case '"':  fputs("\\\"", of); break;
		case '\\': fputs("\\\\", of); break;
		case '\n': fputs("\\n", of); break;
		case '\t': fputs("\\t", of); break;
		default:
			if (c < 0x20)	fprintf(of, "\\x%02x", c);
			else		fputc(c, of);
		}
	}
	fputc('"', of);
}

static void
wwi_rune(FILE *of, u64 cp)
{
	/* #50: the lexer now reads \u/\U, so wide codepoints round-trip as
	 * those escapes (write-twin of lex.c lexunicode). Codepoints <=0xff
	 * keep the \xHH spelling they already round-tripped as. */
	if (cp > 0xffff) {
		fprintf(of, "'\\U%08x'", (unsigned)cp);
		return;
	}
	if (cp > 0xff) {
		fprintf(of, "'\\u%04x'", (unsigned)cp);
		return;
	}
	unsigned char c = (unsigned char)cp;
	fputc('\'', of);
	switch (c) {
	case '\'': fputs("\\'", of); break;
	case '\\': fputs("\\\\", of); break;
	case '\n': fputs("\\n", of); break;
	case '\t': fputs("\\t", of); break;
	default:
		if (c < 0x20 || c >= 0x7f)	fprintf(of, "\\x%02x", c);
		else				fputc(c, of);
	}
	fputc('\'', of);
}

static void
wwi_param(FILE *of, Node *p)
{
	if (p->str && strcmp(p->str, "...") == 0) {	/* C-style FFI `...` */
		fputs("...", of);
		return;
	}
	if (p->str && p->str[0]) {
		fputs(p->str, of);
		fputs(": ", of);
	}
	wwi_type(of, p->lhs);
	if (p->op == TK_ELLIPSIS)			/* Hare `T...` variadic */
		fputs("...", of);
}

static void
wwi_type(FILE *of, Node *t)
{
	if (t == NULL) {	/* absent return type spells void */
		fputs("void", of);
		return;
	}
	switch (t->kind) {
	case N_TNAME:
		fputs(t->str ? t->str : "void", of);
		break;
	case N_TPTR:
		fputc('*', of);
		wwi_type(of, t->lhs);
		break;
	case N_TSLICE:
		fputs("[]", of);
		wwi_type(of, t->lhs);
		break;
	case N_TARRAY:
		fputc('[', of);
		if (t->rhs)	wwi_expr(of, t->rhs);
		else		fputc('_', of);
		fputc(']', of);
		wwi_type(of, t->lhs);
		break;
	case N_TBANG:
		fputc('!', of);
		wwi_type(of, t->lhs);
		break;
	case N_TCHAN:
		fputs("chan ", of);
		wwi_type(of, t->lhs);
		break;
	case N_TFN:
		fputs("fn(", of);
		for (Node *p = t->list; p; p = p->next) {
			if (p != t->list) fputs(", ", of);
			wwi_param(of, p);
		}
		fputs(") ", of);
		wwi_type(of, t->lhs);
		break;
	case N_TSTRUCT:
		/* re-emit the `@packed` attr so the flag round-trips
		 * through sep-compile (harec unparse/type.ha:122-126). */
		fputs(t->packed ? "struct @packed { " : "struct { ", of);
		for (Node *f = t->list; f; f = f->next) {
			if (f != t->list) fputs(", ", of);
			if (f->str && f->str[0]) {
				fputs(f->str, of);
				fputs(": ", of);
			}
			wwi_type(of, f->lhs);
		}
		fputs(" }", of);
		break;
	case N_TTUPLE:
		fputc('(', of);
		for (Node *e = t->list; e; e = e->next) {
			if (e != t->list) fputs(", ", of);
			wwi_type(of, e);
		}
		fputc(')', of);
		break;
	case N_TTAGGED:
		fputc('(', of);
		for (Node *e = t->list; e; e = e->next) {
			if (e != t->list) fputs(" | ", of);
			/* #95: re-emit the spread marker purely syntactically;
			 * the consumer's type-store flattens (ref/hare/hare/
			 * unparse/type.ha:290-300). */
			if (e->op == TK_ELLIPSIS)
				fputs("...", of);
			wwi_type(of, e);
		}
		fputc(')', of);
		break;
	case N_TENUM:
		fputs("enum ", of);
		if (t->lhs) {
			wwi_type(of, t->lhs);
			fputc(' ', of);
		}
		fputs("{ ", of);
		for (Node *m = t->list; m; m = m->next) {
			if (m != t->list) fputs(", ", of);
			fputs(m->str, of);
			if (m->lhs) {
				fputs(" = ", of);
				wwi_expr(of, m->lhs);
			}
		}
		fputs(" }", of);
		break;
	default:
		fatal("wwi: unhandled type node kind %d", t->kind);
	}
}

static void
wwi_expr(FILE *of, Node *e)
{
	if (e == NULL)
		return;
	switch (e->kind) {
	case N_INTLIT:
		fprintf(of, "%llu", (unsigned long long)e->uval);
		if (e->tsuffix) fputs(e->tsuffix, of);
		break;
	case N_IDENT:
	case N_TNAME:
		fputs(e->str, of);
		break;
	case N_DOT:
		wwi_expr(of, e->lhs);
		fputc('.', of);
		fputs(e->str, of);
		break;
	case N_TRUE:	fputs("true", of); break;
	case N_FALSE:	fputs("false", of); break;
	case N_NIL:	fputs("nil", of); break;
	case N_STRLIT:	wwi_quote(of, e->str, e->strlen); break;
	/* A bare rune literal in a const-expr (types::RUNE_MIN = '\0'); casts
	 * never reach here — the checker folds a const cast to an integer
	 * literal before the producer runs (RUNE_MAX `0x10ffff: rune` emits
	 * as the plain int 1114111). */
	case N_RUNELIT:	wwi_rune(of, e->uval); break;
	case N_BIN:
		fputc('(', of);
		wwi_expr(of, e->lhs);
		fprintf(of, " %s ", tokname(e->op));
		wwi_expr(of, e->rhs);
		fputc(')', of);
		break;
	case N_UN:
		fputs(tokname(e->op), of);
		wwi_expr(of, e->lhs);
		break;
	case N_CAST:
		fputc('(', of);
		wwi_expr(of, e->lhs);
		fputs(": ", of);
		wwi_type(of, e->rhs);
		fputc(')', of);
		break;
	default:
		fatal("wwi: unhandled const-expr node kind %d", e->kind);
	}
}

/* Only codegen/link-relevant attributes round-trip into the `.wwi`. Today
 * that is exactly @symbol (the FFI link-symbol override, read back at cgen
 * fficollect — dropping it makes sep-compile emit `CALL malloc` for a
 * `@symbol("rt_malloc")` fn). Named for the class so @align/@offset would
 * slot in here IF ww ever grows field-layout attributes — it has none
 * today (task #47 report). @test is compiler-private package-test metadata. */
static int
wwi_attr_relevant(const char *nm)
{
	return nm && (strcmp(nm, "symbol") == 0
	    || strcmp(nm, "test") == 0);
}

static void
wwi_attrs(FILE *of, Node *d)
{
	for (Node *a = d->attr; a; a = a->next) {
		if (a->kind != N_ATTR || !wwi_attr_relevant(a->str))
			continue;
		fputc('@', of);
		fputs(a->str, of);
		if (a->list) {
			fputc('(', of);
			for (Node *arg = a->list; arg; arg = arg->next) {
				if (arg != a->list) fputs(", ", of);
				wwi_expr(of, arg);
			}
			fputc(')', of);
		}
		fputc(' ', of);
	}
}

static void
wwi_decl(FILE *of, Node *d)
{
	switch (d->kind) {
	case N_FNDECL:
		wwi_attrs(of, d);
		fputs(d->export ? "export fn " : "fn ", of);
		fputs(d->str, of);
		fputc('(', of);
		for (Node *p = d->list; p; p = p->next) {
			if (p != d->list) fputs(", ", of);
			wwi_param(of, p);
		}
		fputs(") ", of);
		wwi_type(of, d->lhs);
		fputs(";\n", of);
		break;
	case N_TYPEDECL:
		fputs(d->export ? "export type " : "type ", of);
		fputs(d->str, of);
		fputs(" = ", of);
		wwi_type(of, d->lhs);
		fputs(";\n", of);
		break;
	case N_DEF:
		fputs(d->export ? "export def " : "def ", of);
		fputs(d->str, of);
		fputs(": ", of);
		wwi_type(of, d->lhs);
		/* An aggregate initializer (N_STRUCTLIT/N_ARRLIT) is a DATA-
		 * global (#52): emit a value-LESS prototype `export def X: T;`.
		 * The defining package's own .o emits the struct/array DATA; the
		 * importer registers the def by TYPE only (the DATA-suppression
		 * if(sep_mode && imported)continue at cgen.c is already in place)
		 * and field/element reads become external LEAQ refs the linker
		 * fills. Boundary (rule 7): this gives up importer-side const-
		 * fold of an aggregate def's FIELDS — a no-op, ww never folds
		 * struct-literal field access, and an aggregate-def field
		 * demanded in a const-fold context stays a LOUD error (task #71). */
		if (d->rhs == NULL || (d->rhs->kind == N_STRUCTLIT
		    || d->rhs->kind == N_ARRLIT)) {
			fputs(";\n", of);
		} else {
			fputs(" = ", of);
			wwi_expr(of, d->rhs);
			fputs(";\n", of);
		}
		break;
	case N_LET:
		fputs(d->export ? "export let " : "let ", of);
		fputs(d->str, of);
		fputs(": ", of);
		if (d->lhs == NULL)
			fatal("wwi: exported let '%s' has no declared type",
			    d->str);
		wwi_type(of, d->lhs);
		fputs(";\n", of);
		break;
	default:
		break;
	}
}

/* deterministic ordering per rob §3. */

struct declent { Node *d; int idx; };
struct useent  { const char *path; int idx; };
struct factent { Node *d; const char *mod; int idx; };

struct factset {
	Checker *c;
	struct declent *privatefacts;
	int nprivate, capprivate;
	struct factent *facts;
	int nfacts, capfacts;
	struct factent *seen;
	int nseen, capseen;
	int bad;
};

static void
wwi_decl_grow(struct declent **v, int *cap, int need)
{
	if (*cap >= need) return;
	int ncap = *cap ? *cap * 2 : 16;
	while (ncap < need) ncap *= 2;
	struct declent *nv = realloc(*v, (size_t)ncap * sizeof *nv);
	if (nv == NULL) fatal("wwi: out of memory");
	*v = nv;
	*cap = ncap;
}

static int
declcmp(const void *a, const void *b)
{
	const struct declent *x = a, *y = b;
	int r = strcmp(x->d->str, y->d->str);	/* symbol name ONLY */
	if (r != 0) return r;
	return x->idx - y->idx;			/* total order, stable */
}

static int
usecmp(const void *a, const void *b)
{
	const struct useent *x = a, *y = b;
	int r = strcmp(x->path, y->path);
	if (r != 0) return r;
	return x->idx - y->idx;
}

static int
factcmp(const void *a, const void *b)
{
	const struct factent *x = a, *y = b;
	int r = strcmp(x->mod, y->mod);
	if (r != 0) return r;
	if (x->d->sourceid != y->d->sourceid)
		return x->d->sourceid - y->d->sourceid;
	int xr = x->d->kind == N_TYPEDECL ? 0 : 1;
	int yr = y->d->kind == N_TYPEDECL ? 0 : 1;
	if (xr != yr) return xr - yr;
	r = strcmp(x->d->str, y->d->str);
	if (r != 0) return r;
	return x->idx - y->idx;
}

static int
wwi_is_decl(Node *d)
{
	return d->kind == N_FNDECL || d->kind == N_TYPEDECL
	    || d->kind == N_DEF || d->kind == N_LET;
}

static int
wwi_has_attr(Node *d, const char *name)
{
	for (Node *a = d ? d->attr : NULL; a; a = a->next)
		if (a->kind == N_ATTR && a->str && strcmp(a->str, name) == 0)
			return 1;
	return 0;
}

static int
wwi_fact_same(struct factent *f, const char *mod, Node *d)
{
	return wwi_mod_eq(f->mod, mod) && f->d->kind == d->kind
	    && strcmp(f->d->str, d->str) == 0;
}

static void
wwi_fact_grow(struct factent **v, int *cap, int need)
{
	if (*cap >= need) return;
	int ncap = *cap ? *cap * 2 : 16;
	while (ncap < need) ncap *= 2;
	struct factent *nv = realloc(*v, (size_t)ncap * sizeof *nv);
	if (nv == NULL) fatal("wwi: out of memory");
	*v = nv;
	*cap = ncap;
}

static Sym *
wwi_valuesym(Checker *c, const char *owner, int source, const char *name)
{
	for (Scope *p = c->top; p; p = p->parent)
		for (Sym *s = p->first; s; s = s->next)
			if (s->kind == SK_DEF && strcmp(s->name, name) == 0
			    && wwi_mod_eq(s->mod, owner))
				return s;
	for (Scope *p = c->top; p; p = p->parent)
		for (Sym *s = p->first; s; s = s->next)
			if (s->kind == SK_DEF && strcmp(s->name, name) == 0
				    && wwi_direct_mod_visible(c, owner, source, s->mod))
					return s;
	return NULL;
}

static void wwi_collect_decl(struct factset*, const char*, Node*);
static void wwi_collect_type(struct factset*, const char*, int, Node*);

static void
wwi_collect_expr(struct factset *fs, const char *owner, int source, Node *e)
{
	if (e == NULL) return;
	Sym *s = NULL;
	if (e->kind == N_IDENT) {
		s = wwi_valuesym(fs->c, owner, source, e->str);
	} else if (e->kind == N_DOT && e->lhs
	    && e->lhs->kind == N_IDENT) {
		const char *mod = wwi_use_path(fs->c, owner, source,
		    e->lhs->str);
		if (mod) s = wwi_valuesym(fs->c, mod, source, e->str);
	}
	if (s && s->decl && s->decl->kind == N_DEF) {
		if (!s->decl->export) {
			errorf(e->pos, "exported declaration references "
			    "unexported def '%s'", e->str);
			fs->bad = 1;
			return;
		}
		wwi_collect_decl(fs, s->mod, s->decl);
		return;
	}
	if (e->kind == N_BIN) {
		wwi_collect_expr(fs, owner, source, e->lhs);
		wwi_collect_expr(fs, owner, source, e->rhs);
	} else if (e->kind == N_UN) {
		wwi_collect_expr(fs, owner, source, e->lhs);
	} else if (e->kind == N_CAST) {
		wwi_collect_expr(fs, owner, source, e->lhs);
		wwi_collect_type(fs, owner, source, e->rhs);
	}
}

static void
wwi_collect_type(struct factset *fs, const char *owner, int source, Node *t)
{
	if (t == NULL) return;
	switch (t->kind) {
	case N_TNAME: {
		Sym *s = wwi_typesym(fs->c, owner, source, t->str);
		if (s && s->decl && s->decl->kind == N_TYPEDECL)
			wwi_collect_decl(fs, s->mod, s->decl);
		break;
	}
	case N_TPTR:
	case N_TSLICE:
	case N_TBANG:
	case N_TCHAN:
		wwi_collect_type(fs, owner, source, t->lhs);
		break;
	case N_TARRAY:
		/* Array length is part of the resolved type identity, not a source
		 * name dependency. Canonicalize it so private constants stay private
		 * and a consumer never needs an implementation def to size the type. */
		if (t->rhs != NULL && t->rhs->kind != N_INTLIT) {
			u64 len;
			if (!check_eval_const(fs->c, t->rhs, owner, source, &len)) {
				errorf(t->pos, "cannot encode array dimension");
				fs->bad = 1;
			} else {
				Node *e = t->rhs;
				e->kind = N_INTLIT;
				e->uval = len;
				e->tsuffix = NULL;
				e->lhs = e->rhs = e->list = NULL;
			}
		}
		wwi_collect_type(fs, owner, source, t->lhs);
		break;
	case N_TFN:
		for (Node *p = t->list; p; p = p->next)
			wwi_collect_type(fs, owner, source, p->lhs);
		wwi_collect_type(fs, owner, source, t->lhs);
		break;
	case N_TSTRUCT:
		for (Node *f = t->list; f; f = f->next)
			wwi_collect_type(fs, owner, source, f->lhs);
		break;
	case N_TTAGGED:
	case N_TTUPLE:
		for (Node *e = t->list; e; e = e->next)
			wwi_collect_type(fs, owner, source, e);
		break;
	case N_TENUM:
		wwi_collect_type(fs, owner, source, t->lhs);
		/* Member identifiers are enum-local prior-sibling references, not
		 * package defs; the complete member list already carries their facts. */
		break;
	default:
		break;
	}
}

static void
wwi_collect_decl(struct factset *fs, const char *owner, Node *d)
{
	for (int i = 0; i < fs->nseen; i++)
		if (wwi_fact_same(&fs->seen[i], owner, d))
			return;
	wwi_fact_grow(&fs->seen, &fs->capseen, fs->nseen + 1);
	fs->seen[fs->nseen] = (struct factent){d, owner, fs->nseen};
	fs->nseen++;

	if (owner == NULL && !d->export) {
		if (d->kind != N_TYPEDECL) {
			errorf(d->pos, "exported declaration references unexported "
			    "def '%s'", d->str);
			fs->bad = 1;
			return;
		}
		wwi_decl_grow(&fs->privatefacts, &fs->capprivate,
		    fs->nprivate + 1);
		fs->privatefacts[fs->nprivate] =
		    (struct declent){d, fs->nprivate};
		fs->nprivate++;
	} else if (owner != NULL) {
		if (!d->export && d->kind != N_TYPEDECL) {
			errorf(d->pos, "exported declaration references unexported "
			    "%s '%s'", d->kind == N_TYPEDECL ? "type" : "def",
			    d->str);
			fs->bad = 1;
			return;
		}
		wwi_fact_grow(&fs->facts, &fs->capfacts, fs->nfacts + 1);
		fs->facts[fs->nfacts] = (struct factent){d, owner, fs->nfacts};
		fs->nfacts++;
	}

	switch (d->kind) {
	case N_FNDECL:
		for (Node *p = d->list; p; p = p->next)
			wwi_collect_type(fs, owner, d->sourceid, p->lhs);
		wwi_collect_type(fs, owner, d->sourceid, d->lhs);
		break;
	case N_TYPEDECL:
		wwi_collect_type(fs, owner, d->sourceid, d->lhs);
		break;
	case N_DEF:
		wwi_collect_type(fs, owner, d->sourceid, d->lhs);
		wwi_collect_expr(fs, owner, d->sourceid, d->rhs);
		break;
	case N_LET:
		wwi_collect_type(fs, owner, d->sourceid, d->lhs);
		break;
	default:
		break;
	}
}

static int
wwi_use_owned(Node *u, const char *owner, int source)
{
	return u->kind == N_USE && u->imported != 0
	    && u->sourceid == source && wwi_mod_eq(u->module, owner);
}

static void
wwi_emit_imports(FILE *of, Node *file, const char *owner, int source,
    int imported)
{
	int nuse = 0;
	for (Node *u = file->list; u; u = u->next) {
		int owned = imported ? wwi_use_owned(u, owner, source)
		    : u->kind == N_USE && u->imported == 0
			&& u->sourceid == source;
		if (owned) nuse++;
	}
	if (nuse == 0) return;
	struct useent *us = malloc((size_t)nuse * sizeof *us);
	if (us == NULL) fatal("wwi: out of memory");
	int k = 0;
	for (Node *u = file->list; u; u = u->next) {
		int owned = imported ? wwi_use_owned(u, owner, source)
		    : u->kind == N_USE && u->imported == 0
			&& u->sourceid == source;
		if (!owned) continue;
		us[k].path = u->usepath ? u->usepath : u->str;
		us[k].idx = k;
		k++;
	}
	qsort(us, (size_t)nuse, sizeof *us, usecmp);
	const char *previous = NULL;
	for (int i = 0; i < nuse; i++) {
		if (previous && strcmp(previous, us[i].path) == 0) continue;
		fprintf(of, "import %s;\n", us[i].path);
		previous = us[i].path;
	}
	free(us);
}

static int
wwi_primary_section_has(Checker *c, Node *file, struct factset *fs,
    struct declent *exports, int nexports, int source)
{
	for (Node *u = file->list; u; u = u->next)
		if (u->kind == N_USE && u->imported == 0
		    && u->sourceid == source)
			return 1;
	for (int i = 0; i < fs->nprivate; i++)
		if (fs->privatefacts[i].d->sourceid == source) return 1;
	for (int i = 0; i < nexports; i++)
		if (exports[i].d->sourceid == source) return 1;
	if (c->is_test_package)
		for (Node *d = file->list; d; d = d->next)
			if (wwi_primary(d) && d->sourceid == source
			    && d->kind == N_FNDECL && !d->export
			    && wwi_has_attr(d, "test"))
				return 1;
	return 0;
}

static int
wwi_first_primary_source(Node *file)
{
	int found = 0;
	int source = 0;
	for (Node *d = file->list; d; d = d->next) {
		if (!wwi_primary(d)) continue;
		if (!found || d->sourceid < source) {
			source = d->sourceid;
			found = 1;
		}
	}
	return found ? source : file->sourceid;
}

static void
wwi_emit_primary_section(Checker *c, FILE *of, Node *file,
    struct factset *fs, struct declent *exports, int nexports,
    const char *owner, const char *pkg, int source)
{
	if (owner != NULL && owner[0] != '\0')
		fprintf(of, "//ww:module %s\n", owner);
	fprintf(of, "package %s;\n", pkg && pkg[0] ? pkg : "main");
	wwi_emit_imports(of, file, owner, source, 0);
	for (int i = 0; i < fs->nprivate; i++)
		if (fs->privatefacts[i].d->sourceid == source)
			wwi_decl(of, fs->privatefacts[i].d);
	if (c->is_test_package)
		for (Node *d = file->list; d; d = d->next)
			if (wwi_primary(d) && d->sourceid == source
			    && d->kind == N_FNDECL && !d->export
			    && wwi_has_attr(d, "test"))
				wwi_decl(of, d);
	for (int i = 0; i < nexports; i++)
		if (exports[i].d->sourceid == source)
			wwi_decl(of, exports[i].d);
}

int
wwi_emit(Checker *c, FILE *of, Node *file)
{
	/* §5: check_exported_type FIRST, before any byte is written — a
	 * producer without it can emit a dangling `.wwi`. */
	int bad = 0;
	for (Node *d = file->list; d; d = d->next) {
		if (!wwi_primary(d) || !d->export || !wwi_is_decl(d))
			continue;
		bad |= wwi_check_decl(c, d);
	}
	if (bad)
		return 1;

	/* Relocate the exported API's reachable foreign type facts into this
	 * package's own interface. The driver remains deliberately ignorant of
	 * the representation and will pass only this artifact for a direct dep. */
	struct factset fs = {.c = c};
	for (Node *d = file->list; d; d = d->next) {
		if (!wwi_primary(d) || !d->export || !wwi_is_decl(d)) continue;
		wwi_collect_decl(&fs, NULL, d);
	}
	if (fs.bad) {
		free(fs.privatefacts);
		free(fs.facts);
		free(fs.seen);
		return 1;
	}
	if (fs.nprivate > 1)
		qsort(fs.privatefacts, (size_t)fs.nprivate,
		    sizeof *fs.privatefacts, declcmp);
	if (fs.nfacts > 1)
		qsort(fs.facts, (size_t)fs.nfacts, sizeof *fs.facts, factcmp);

	/* Exported declarations are sorted within their source-file sections. */
	int ndecl = 0;
	for (Node *d = file->list; d; d = d->next)
		if (wwi_primary(d) && d->export && wwi_is_decl(d))
			ndecl++;
	struct declent *ds = NULL;
	if (ndecl > 0) {
		ds = malloc((size_t)ndecl * sizeof *ds);
		if (ds == NULL) fatal("wwi: out of memory");
		int k = 0;
		for (Node *d = file->list; d; d = d->next) {
			if (!wwi_primary(d) || !d->export || !wwi_is_decl(d))
				continue;
			ds[k].d = d;
			ds[k].idx = k;
			k++;
		}
		qsort(ds, (size_t)ndecl, sizeof *ds, declcmp);
	}

	/* Canonical ownership, declared name, and lexical source scope are three
	 * independent export facts. Repeated owner sections preserve the file that
	 * owns each binding while keeping every symbol/action keyed by OWNER. */
	int nsection = 0;
	for (Node *p = file->body; p; p = p->next) {
		if (p->imported || !wwi_primary_section_has(c, file, &fs, ds,
		    ndecl, p->sourceid))
			continue;
		const char *owner = p->module && p->module[0]
		    ? p->module : file->module;
		const char *pkg = p->pkgname && p->pkgname[0]
		    ? p->pkgname : file->pkgname;
		wwi_emit_primary_section(c, of, file, &fs, ds, ndecl, owner,
		    pkg, p->sourceid);
		nsection++;
	}
	if (nsection == 0) {
		const char *pkg = file->pkgname && file->pkgname[0]
		    ? file->pkgname : "main";
		wwi_emit_primary_section(c, of, file, &fs, ds, ndecl,
		    file->module, pkg, wwi_first_primary_source(file));
	}
	free(ds);

	/* Compiler-owned public fact closure. A module marker changes semantic
	 * ownership without making the namespace a source import of the eventual
	 * consumer; direct visibility continues to come solely from its own N_USE. */
	const char *lastmod = NULL;
	int lastsource = -1;
	for (int i = 0; i < fs.nfacts; i++) {
		struct factent *f = &fs.facts[i];
		if (lastmod == NULL || strcmp(lastmod, f->mod) != 0
		    || lastsource != f->d->sourceid) {
			const char *dot = strrchr(f->mod, '.');
			const char *factpkg = f->d->pkgname && f->d->pkgname[0]
			    ? f->d->pkgname : (dot ? dot + 1 : f->mod);
			fprintf(of, "//ww:module %s\n", f->mod);
			fprintf(of, "package %s;\n", factpkg);
			wwi_emit_imports(of, file, f->mod, f->d->sourceid, 1);
			lastmod = f->mod;
			lastsource = f->d->sourceid;
		}
		wwi_decl(of, f->d);
	}
	free(fs.privatefacts);
	free(fs.facts);
	free(fs.seen);
	return 0;
}