// Standalone unit tests for the VT1200 board register model.
//   g++ -std=c++17 -o /tmp/t vt1200_board.cpp test_vt1200_board.cpp && /tmp/t
#include "vt1200_board.h"
#include <cassert>
#include <cstdio>

static int failures = 0;
#define CHECK(cond) do { if (!(cond)) { \
    std::printf("FAIL %s:%d  %s\n", __FILE__, __LINE__, #cond); failures++; } } while (0)

static void test_default_read(void)
{
    vt1200_board b;
    b.set_default(0x0000);
    CHECK(b.read(VT1200_WIN2 + VT1200_OFF_STATUS) == 0x0000);
}

static void test_override_read(void)
{
    vt1200_board b;
    b.set_override(VT1200_WIN2 + VT1200_OFF_STATUS, 0x00b7);
    CHECK(b.read(VT1200_WIN2 + VT1200_OFF_STATUS) == 0x00b7);
}

static void test_monitor_switch_is_mixed_with_latches(void)
{
    vt1200_board b;
    b.set_monitor_switch(7);                              // position 7 -> bits 4-6 = 0x70
    b.write(VT1200_WIN3 + VT1200_OFF_SWITCH, 0x0001);     // output latch writes bit 0
    const uint16_t v = b.read(VT1200_WIN3 + VT1200_OFF_SWITCH);
    CHECK((v & 0x0070) == 0x0070);           // switch bits read back as input
    CHECK((v & 0x0001) == 0x0001);           // output bits read back as latched
}

static void test_busy_bit_arms_on_write_and_clears(void)
{
    vt1200_board b;
    b.set_model_handshake(true);
    b.set_busy_ticks(2);
    const uint32_t status = VT1200_WIN2 + VT1200_OFF_STATUS;
    const uint32_t cmd    = VT1200_WIN2 + VT1200_OFF_CMD;

    CHECK((b.read(status) & 0x0001) == 0x0000);   // idle
    b.write(cmd, 0x00ca);                          // command arms it
    CHECK((b.read(status) & 0x0001) == 0x0001);   // busy
    b.tick();
    CHECK((b.read(status) & 0x0001) == 0x0001);   // still busy
    b.tick();
    CHECK((b.read(status) & 0x0001) == 0x0000);   // done
}

static void test_windows_are_independent(void)
{
    vt1200_board b;
    b.set_model_handshake(true);
    b.set_window_busy_ticks(VT1200_WIN2, 1);
    b.set_window_busy_ticks(VT1200_WIN3, 3);

    b.write(VT1200_WIN2 + VT1200_OFF_CMD, 0x0001);
    b.write(VT1200_WIN3 + VT1200_OFF_CMD, 0x0001);
    CHECK((b.read(VT1200_WIN2 + VT1200_OFF_STATUS) & 1) == 1);
    CHECK((b.read(VT1200_WIN3 + VT1200_OFF_STATUS) & 1) == 1);

    b.tick();
    CHECK((b.read(VT1200_WIN2 + VT1200_OFF_STATUS) & 1) == 0);   // WIN2 finished
    CHECK((b.read(VT1200_WIN3 + VT1200_OFF_STATUS) & 1) == 1);   // WIN3 still busy
}

static void test_monitor_switch_accepts_raw_bits_or_position(void)
{
    vt1200_board raw;
    raw.set_monitor_switch(0x70);                         // raw register bits
    raw.write(VT1200_WIN3 + VT1200_OFF_SWITCH, 0x0001);
    CHECK((raw.read(VT1200_WIN3 + VT1200_OFF_SWITCH) & 0x0070) == 0x0070);

    vt1200_board pos;
    pos.set_monitor_switch(7);                            // position 7
    pos.write(VT1200_WIN3 + VT1200_OFF_SWITCH, 0x0001);
    CHECK((pos.read(VT1200_WIN3 + VT1200_OFF_SWITCH) & 0x0070) == 0x0070);
}

static void test_switch_mix_only_when_configured(void)
{
    vt1200_board b;                                       // no set_monitor_switch call
    b.write(VT1200_WIN3 + VT1200_OFF_SWITCH, 0x0070);
    CHECK(b.read(VT1200_WIN3 + VT1200_OFF_SWITCH) == 0x0070);   // returned verbatim
}

static void test_dma_pair_command_completes(void)
{
    vt1200_board b;
    b.set_model_handshake(true);
    b.set_dma_ticks(2);

    b.write(VT1200_WIN0, 0x0000);            // data port first (as the firmware does)
    b.write(VT1200_WIN1, 0x0001);            // then a command
    CHECK(b.read(VT1200_WIN1) == 0x0001);    // accepted

    b.tick(); b.tick();
    CHECK(b.read(VT1200_WIN1) == 0x0000);    // completed
}

// The two timers the sweep tunes (window busy and DMA completion) must advance
// on the same tick(), or a later slower timer would silently stretch the other.
static void test_one_tick_advances_window_and_dma_timers(void)
{
    vt1200_board b;
    b.set_model_handshake(true);
    b.set_window_busy_ticks(VT1200_WIN2, 2);
    b.set_dma_ticks(2);

    b.write(VT1200_WIN2 + VT1200_OFF_CMD, 0x0001);   // arms WIN2's busy bit
    b.write(VT1200_WIN0, 0x0000);                    // data port first
    b.write(VT1200_WIN1, 0x0042);                    // then a DMA command

    b.tick();                                        // one frame: both advance
    CHECK((b.read(VT1200_WIN2 + VT1200_OFF_STATUS) & 1) == 1);
    CHECK(b.read(VT1200_WIN1) == 0x0042);

    b.tick();
    CHECK((b.read(VT1200_WIN2 + VT1200_OFF_STATUS) & 1) == 0);
    CHECK(b.read(VT1200_WIN1) == 0x0000);
}

int main(void)
{
    test_default_read();
    test_override_read();
    test_monitor_switch_is_mixed_with_latches();
    test_busy_bit_arms_on_write_and_clears();
    test_windows_are_independent();
    test_monitor_switch_accepts_raw_bits_or_position();
    test_switch_mix_only_when_configured();
    test_dma_pair_command_completes();
    test_one_tick_advances_window_and_dma_timers();
    std::printf(failures ? "%d FAILURE(S)\n" : "all board tests passed\n", failures);
    return failures ? 1 : 0;
}