// memiotest — exercises lib/memio. Run with `out/bin/ww run lib/memio/memiotest.ww`.
//
// Every @test enumerates parallel `[N]T` arrays of inputs and
// expectations, then iterates one body across them. Parallel arrays
// (rather than `[N]struct{...}`) sidestep the cstage cgen's chained
// `arr[i].field` store gap (task #6).

package memio;

import bytes;
import io;
import memio;
import os;

// signalled — bumped by main before each test so a failing exit code
// pinpoints the offending case.
let signalled: i32 = 0;

fn fail() void = { os.exit(signalled + 10); };

fn putstr(s: str, into: []u8, off: i32) i32 = {
	let i: i32 = 0;
	for (i < s.len) {
		into[off + i] = s[i];
		i += 1;
	};
	return off + s.len;
};

// ---- fixedread: read sizes drive partial / full / eof outcomes ----------

@test fn fixedread() void = {
	let arr: [8]u8;
	arr[0] = 1u8; arr[1] = 2u8; arr[2] = 3u8; arr[3] = 4u8;
	arr[4] = 5u8; arr[5] = 6u8; arr[6] = 7u8; arr[7] = 8u8;

	// (request, wantn, wantfirst, wantlast, weof)
	// 5 rows: under-remaining, full slot, last-byte-only, post-end, 0-len-at-end.
	let req:   [5]i32;
	let wantn: [5]i32;
	let wantf: [5]u8;
	let wantl: [5]u8;
	let weof:  [5]i32;
	req[0]=3; wantn[0]=3; wantf[0]=1u8; wantl[0]=3u8; weof[0]=0;
	req[1]=4; wantn[1]=4; wantf[1]=4u8; wantl[1]=7u8; weof[1]=0;
	req[2]=5; wantn[2]=1; wantf[2]=8u8; wantl[2]=8u8; weof[2]=0;
	req[3]=1; wantn[3]=0; wantf[3]=0u8; wantl[3]=0u8; weof[3]=1;
	req[4]=0; wantn[4]=0; wantf[4]=0u8; wantl[4]=0u8; weof[4]=1;

	let mem: memio.state;
	let s: io.stream;
	memio.fixed(&mem, &s, arr[0:8]);

	let out: [8]u8;
	let i: i32 = 0;
	for (i < 5) {
		// Clear out so spot checks read real data, not stale bytes.
		let k: i32 = 0;
		for (k < 8) { out[k] = 0u8; k += 1; };

		let r: (i32 | io.eof | io.closed) = io.read(&s, out[0:req[i]]);
		match (r) {
		case let n: i32 => {
			if (weof[i] != 0) { fail(); };
			if (n != wantn[i]) { fail(); };
			if (n > 0 && out[0] != wantf[i]) { fail(); };
			if (n > 0 && out[n - 1] != wantl[i]) { fail(); };
		};
		case io.eof => { if (weof[i] == 0) { fail(); }; };
		case io.closed => fail();
		};
		i += 1;
	};

	// closenoop on a fixed stream returns void.
	let c: (void | io.closed) = io.close(&s);
	match (c) { case void => {}; case io.closed => fail(); };
};

// ---- fixedwritecases: full-fit / exact-fill / partial / overflow -------------

@test fn fixedwritecases() void = {
	let dst: [16]u8;
	let mem: memio.state;
	let s: io.stream;
	memio.fixed(&mem, &s, dst[0:16]);

	// One flat source; rows index into it via (off, len). Sequence:
	// "hello " (6), "world!!" (7), "XXXXXXX" (7), "Y" (1).
	let src: [32]u8;
	let _: i32 = putstr("hello world!!XXXXXXXY", src[0:32], 0);

	// (srcoff, inlen, wantn) — wantn diverges from inlen on the
	// partial and overflow rows.
	let off:   [4]i32;
	let ln:    [4]i32;
	let wantn: [4]i32;
	off[0]=0;  ln[0]=6; wantn[0]=6;	// full fit
	off[1]=6;  ln[1]=7; wantn[1]=7;	// exact-fills cap (pos=13)
	off[2]=13; ln[2]=7; wantn[2]=3;	// partial: 3 free
	off[3]=20; ln[3]=1; wantn[3]=0;	// overflow: 0 free → 0

	let i: i32 = 0;
	for (i < 4) {
		let lo: i32 = off[i];
		let hi: i32 = lo + ln[i];
		let r: (i32 | io.closed) = io.write(&s, src[lo:hi]);
		match (r) {
		case let n: i32 => { if (n != wantn[i]) { fail(); }; };
		case io.closed => fail();
		};
		i += 1;
	};

	let want: [16]u8;
	let _: i32 = putstr("hello world!!XXX", want[0:16], 0);
	if (!bytes.equal(dst[0:16], want[0:16])) { fail(); };

	// 0-byte write is always 0 with no side effects.
	let r0: (i32 | io.closed) = io.write(&s, src[0:0]);
	match (r0) {
	case let n: i32 => { if (n != 0) { fail(); }; };
	case io.closed => fail();
	};

	let c: (void | io.closed) = io.close(&s);
	match (c) { case void => {}; case io.closed => fail(); };
};

// ---- dynamicgrow: every cap doubling exercised --------------------------

// Drive grow 0 → 8 → 16 → 32 by writing sized chunks. Verify
// accumulated `pos` after each step.
@test fn dynamicgrow() void = {
	let mem: memio.state;
	let s: io.stream;
	memio.dynamic(&mem, &s);

	let src: [32]u8;
	let _: i32 = putstr("abcdefghijklmnopqrstuvwxyz012345", src[0:32], 0);

	// (chunkn, totaln) — cap transitions: 0→8 at row 0; 8→16 at row 2;
	// 16→32 at row 4.
	let chunk: [5]i32;
	let total: [5]i32;
	chunk[0]=3;  total[0]=3;
	chunk[1]=5;  total[1]=8;
	chunk[2]=1;  total[2]=9;
	chunk[3]=7;  total[3]=16;
	chunk[4]=10; total[4]=26;

	let off: i32 = 0;
	let i:   i32 = 0;
	for (i < 5) {
		let lo: i32 = off;
		let hi: i32 = lo + chunk[i];
		let r: (i32 | io.closed) = io.write(&s, src[lo:hi]);
		match (r) {
		case let n: i32 => { if (n != chunk[i]) { fail(); }; };
		case io.closed => fail();
		};
		if (memio.buffer(&mem).len != total[i]) { fail(); };
		off += chunk[i];
		i += 1;
	};

	if (!bytes.equal(memio.buffer(&mem), src[0:26])) { fail(); };

	let c: (void | io.closed) = io.close(&s);
	match (c) { case void => {}; case io.closed => fail(); };
};

// ---- dynamicreset: write / reset / write cycles -------------------------

// op=0 writes `ln` bytes from a rolling source; op=1 resets and ignores
// ln. After each row the accumulated len must equal `want`.
@test fn dynamicreset() void = {
	let mem: memio.state;
	let s: io.stream;
	memio.dynamic(&mem, &s);

	let src: [16]u8;
	src[0]=10u8; src[1]=20u8; src[2]=30u8; src[3]=40u8;
	src[4]=50u8; src[5]=60u8; src[6]=70u8; src[7]=80u8;

	let op:   [6]i32;
	let ln:   [6]i32;
	let want: [6]i32;
	op[0]=0; ln[0]=5; want[0]=5;	// initial write
	op[1]=1; ln[1]=0; want[1]=0;	// reset (after writes)
	op[2]=0; ln[2]=3; want[2]=3;	// refill from 0
	op[3]=0; ln[3]=2; want[3]=5;	// continue
	op[4]=1; ln[4]=0; want[4]=0;	// reset (after partial)
	op[5]=0; ln[5]=8; want[5]=8;	// larger refill

	let off: i32 = 0;
	let i:   i32 = 0;
	for (i < 6) {
		if (op[i] == 1) {
			memio.reset(&mem);
			off = 0;
		} else {
			let lo: i32 = off;
			let hi: i32 = lo + ln[i];
			let r: (i32 | io.closed) = io.write(&s, src[lo:hi]);
			match (r) {
			case let n: i32 => { if (n != ln[i]) { fail(); }; };
			case io.closed => fail();
			};
			off += ln[i];
		};
		if (memio.buffer(&mem).len != want[i]) { fail(); };
		i += 1;
	};

	if (!bytes.equal(memio.buffer(&mem), src[0:8])) { fail(); };

	let c: (void | io.closed) = io.close(&s);
	match (c) { case void => {}; case io.closed => fail(); };
};

// ---- borrowedread: under / exact / over / 0-byte ------------------------

@test fn borrowedreadcases() void = {
	let arr: [6]u8;
	arr[0]=0u8; arr[1]=1u8; arr[2]=2u8; arr[3]=3u8; arr[4]=4u8; arr[5]=5u8;

	let mem: memio.state;
	let s: io.stream;
	memio.fixed(&mem, &s, arr[0:6]);

	// (amt, wantfirst, wantlast, weof)
	let amt:  [4]i32;
	let wf:   [4]u8;
	let wl:   [4]u8;
	let weof: [4]i32;
	amt[0]=4; wf[0]=0u8; wl[0]=3u8; weof[0]=0;	// under remaining
	amt[1]=2; wf[1]=4u8; wl[1]=5u8; weof[1]=0;	// exact remaining
	amt[2]=1; wf[2]=0u8; wl[2]=0u8; weof[2]=1;	// past end → eof
	amt[3]=0; wf[3]=0u8; wl[3]=0u8; weof[3]=0;	// 0-byte view always ok

	let i: i32 = 0;
	for (i < 4) {
		let r: ([]u8 | io.eof) = memio.borrowedread(&mem, amt[i]);
		match (r) {
		case let v: []u8 => {
			if (weof[i] != 0) { fail(); };
			if (v.len != amt[i]) { fail(); };
			if (v.len > 0 && v[0] != wf[i]) { fail(); };
			if (v.len > 0 && v[v.len - 1] != wl[i]) { fail(); };
		};
		case io.eof => { if (weof[i] == 0) { fail(); }; };
		};
		i += 1;
	};
};

// ---- stringview: len + endpoints track pos across appends ---------------

@test fn stringview() void = {
	let mem: memio.state;
	let s: io.stream;
	memio.dynamic(&mem, &s);

	if (memio.string(&mem).len != 0) { fail(); };

	let src: [32]u8;
	let _: i32 = putstr("hello world!!", src[0:32], 0);

	// (srcoff, inlen, wantacc, wantfirst, wantlast)
	let off:  [3]i32;
	let ln:   [3]i32;
	let want: [3]i32;
	let wf:   [3]u8;
	let wl:   [3]u8;
	off[0]=0;  ln[0]=5; want[0]=5;  wf[0]=104u8; wl[0]=111u8;	// "hello"   h..o
	off[1]=5;  ln[1]=6; want[1]=11; wf[1]=104u8; wl[1]=100u8;	// +" world" h..d
	off[2]=11; ln[2]=2; want[2]=13; wf[2]=104u8; wl[2]=33u8;	// +"!!"     h..!

	let i: i32 = 0;
	for (i < 3) {
		let lo: i32 = off[i];
		let hi: i32 = lo + ln[i];
		let r: (i32 | io.closed) = io.write(&s, src[lo:hi]);
		match (r) { case let n: i32 => {}; case io.closed => fail(); };
		let v: str = memio.string(&mem);
		if (v.len != want[i]) { fail(); };
		if (v[0] != wf[i]) { fail(); };
		if (v[v.len - 1] != wl[i]) { fail(); };
		i += 1;
	};

	let c: (void | io.closed) = io.close(&s);
	match (c) { case void => {}; case io.closed => fail(); };
};

// ---- dynamicfromseed: ownership-transferred seed, read then write -------

@test fn dynamicfromseed() void = {
	// Build a heap-allocated seed via append (rt_ensure path), then
	// hand ownership to memio. dynamicclose then frees `seed.cap`
	// bytes — the regression that motivated the `m.cap = buf.cap`
	// fix in lib/memio/memio.ww.
	let seed: []u8;
	seed.ptr = nil; seed.len = 0; seed.cap = 0;
	append(seed, 100u8, 101u8, 102u8, 103u8);

	let mem: memio.state;
	let s: io.stream;
	memio.dynamicfrom(&mem, &s, seed);

	// (readn, wantbyte, weof)
	let rn:   [5]i32;
	let want: [5]u8;
	let weof: [5]i32;
	rn[0]=1; want[0]=100u8; weof[0]=0;
	rn[1]=1; want[1]=101u8; weof[1]=0;
	rn[2]=1; want[2]=102u8; weof[2]=0;
	rn[3]=1; want[3]=103u8; weof[3]=0;
	rn[4]=1; want[4]=0u8;   weof[4]=1;	// past seed end → eof

	let out: [4]u8;
	let i: i32 = 0;
	for (i < 5) {
		let r: (i32 | io.eof | io.closed) = io.read(&s, out[0:rn[i]]);
		match (r) {
		case let n: i32 => {
			if (weof[i] != 0) { fail(); };
			if (n != rn[i]) { fail(); };
			if (out[0] != want[i]) { fail(); };
		};
		case io.eof => { if (weof[i] == 0) { fail(); }; };
		case io.closed => fail();
		};
		i += 1;
	};

	// Now write extends past the seed; grow path runs and close
	// must free the (post-grow) cap, not the seed cap.
	let extra: [4]u8;
	extra[0]=200u8; extra[1]=201u8; extra[2]=202u8; extra[3]=203u8;
	let w: (i32 | io.closed) = io.write(&s, extra[0:4]);
	match (w) {
	case let n: i32 => { if (n != 4) { fail(); }; };
	case io.closed => fail();
	};

	let c: (void | io.closed) = io.close(&s);
	match (c) { case void => {}; case io.closed => fail(); };
};

export fn main() i32 = {
	signalled = 1; fixedread();
	signalled = 2; fixedwritecases();
	signalled = 3; dynamicgrow();
	signalled = 4; dynamicreset();
	signalled = 5; borrowedreadcases();
	signalled = 6; stringview();
	signalled = 7; dynamicfromseed();
	return 0;
};