/*
 * GSP vGPU-IO Driver Mock Test
 * Tests driver logic with mocked hardware interfaces
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <linux/mutex.h>
#include <linux/list.h>
#include <linux/idr.h>
#include <linux/kref.h>
#include <linux/completion.h>
#include <linux/atomic.h>

#define TEST_PASS 0
#define TEST_FAIL -1

static int test_count = 0;
static int pass_count = 0;
static int fail_count = 0;

#define TEST_ASSERT(cond, msg) \
    do { \
        test_count++; \
        if (cond) { \
            pass_count++; \
            pr_info("PASS: %s\n", msg); \
        } else { \
            fail_count++; \
            pr_err("FAIL: %s\n", msg); \
        } \
    } while (0)

#define TEST_ASSERT_EQ(a, b, msg) \
    TEST_ASSERT((a) == (b), msg " (expected " #b ", got " #a ")")

/* ============================================================
 * Mock Hardware Abstraction
 * ============================================================ */

struct mock_hw {
    u64 bar0_regs[256];
    u64 bar1_regs[256];
    u8 *fw_memory;
    size_t fw_size;
    bool doorbell_triggered;
    u32 doorbell_count;
    spinlock_t lock;
};

static struct mock_hw *mock_hw_create(void)
{
    struct mock_hw *hw = kzalloc(sizeof(*hw), GFP_KERNEL);
    if (!hw)
        return NULL;

    hw->fw_memory = vmalloc(32 * 1024 * 1024);  // 32MB
    if (!hw->fw_memory) {
        kfree(hw);
        return NULL;
    }
    hw->fw_size = 32 * 1024 * 1024;
    spin_lock_init(&hw->lock);
    return hw;
}

static void mock_hw_destroy(struct mock_hw *hw)
{
    if (!hw)
        return;
    vfree(hw->fw_memory);
    kfree(hw);
}

static void mock_hw_write_bar0(struct mock_hw *hw, u32 offset, u32 value)
{
    unsigned long flags;
    spin_lock_irqsave(&hw->lock, flags);
    if (offset / 4 < 256)
        hw->bar0_regs[offset / 4] = value;
    if (offset == 0x1000) {  // Doorbell
        hw->doorbell_triggered = true;
        hw->doorbell_count++;
    }
    spin_unlock_irqrestore(&hw->lock, flags);
}

static u32 mock_hw_read_bar0(struct mock_hw *hw, u32 offset)
{
    unsigned long flags;
    u32 value = 0;
    spin_lock_irqsave(&hw->lock, flags);
    if (offset / 4 < 256)
        value = hw->bar0_regs[offset / 4];
    spin_unlock_irqrestore(&hw->lock, flags);
    return value;
}

static void mock_hw_write_bar1(struct mock_hw *hw, u64 offset, u64 value)
{
    unsigned long flags;
    spin_lock_irqsave(&hw->lock, flags);
    if (offset < hw->fw_size)
        *(u64 *)(hw->fw_memory + offset) = value;
    spin_unlock_irqrestore(&hw->lock, flags);
}

static u64 mock_hw_read_bar1(struct mock_hw *hw, u64 offset)
{
    unsigned long flags;
    u64 value = 0;
    spin_lock_irqsave(&hw->lock, flags);
    if (offset < hw->fw_size)
        value = *(u64 *)(hw->fw_memory + offset);
    spin_unlock_irqrestore(&hw->lock, flags);
    return value;
}

/* ============================================================
 * Mock VF Operations
 * ============================================================ */

struct mock_vf {
    u32 id;
    u64 bar1_offset;
    u64 bar1_size;
    u64 pt_base;
    u64 pt_size;
    u64 cmd_base;
    u64 cmd_size;
    bool active;
    struct {
        u64 aperture_offset;
        u64 aperture_size;
        bool force_access;
        u32 force_vf;
    } bar_state;
    struct list_head wpr_list;
    struct mutex lock;
};

struct mock_wpr_region {
    struct list_head list;
    u64 base;
    u64 size;
    u32 flags;
};

static struct mock_vf *mock_vf_create(u32 id, u64 bar1_offset, u64 bar1_size,
                                       u64 pt_base, u64 pt_size,
                                       u64 cmd_base, u64 cmd_size)
{
    struct mock_vf *vf = kzalloc(sizeof(*vf), GFP_KERNEL);
    if (!vf)
        return NULL;

    vf->id = id;
    vf->bar1_offset = bar1_offset;
    vf->bar1_size = bar1_size;
    vf->pt_base = pt_base;
    vf->pt_size = pt_size;
    vf->cmd_base = cmd_base;
    vf->cmd_size = cmd_size;
    vf->active = true;
    INIT_LIST_HEAD(&vf->wpr_list);
    mutex_init(&vf->lock);

    vf->bar_state.aperture_offset = bar1_offset;
    vf->bar_state.aperture_size = bar1_size;
    vf->bar_state.force_access = false;
    vf->bar_state.force_vf = 0;

    return vf;
}

static void mock_vf_destroy(struct mock_vf *vf)
{
    if (!vf)
        return;

    struct mock_wpr_region *rgn, *tmp;
    mutex_lock(&vf->lock);
    list_for_each_entry_safe(rgn, tmp, &vf->wpr_list, list) {
        list_del(&rgn->list);
        kfree(rgn);
    }
    mutex_unlock(&vf->lock);

    kfree(vf);
}

static int mock_vf_wpr_add(struct mock_vf *vf, u64 base, u64 size, u32 flags)
{
    struct mock_wpr_region *rgn = kzalloc(sizeof(*rgn), GFP_KERNEL);
    if (!rgn)
        return -ENOMEM;

    rgn->base = base;
    rgn->size = size;
    rgn->flags = flags;

    mutex_lock(&vf->lock);
    list_add(&rgn->list, &vf->wpr_list);
    mutex_unlock(&vf->lock);

    return 0;
}

static int mock_vf_wpr_remove(struct mock_vf *vf, u64 base)
{
    struct mock_wpr_region *rgn, *tmp;
    bool found = false;

    mutex_lock(&vf->lock);
    list_for_each_entry_safe(rgn, tmp, &vf->wpr_list, list) {
        if (rgn->base == base) {
            list_del(&rgn->list);
            kfree(rgn);
            found = true;
            break;
        }
    }
    mutex_unlock(&vf->lock);

    return found ? 0 : -ENOENT;
}

/* ============================================================
 * Mock RPC Client
 * ============================================================ */

struct mock_rpc_client {
    u32 seq;
    u32 pending_seq[64];
    u32 pending_count;
    struct mutex lock;
};

static struct mock_rpc_client *mock_rpc_create(void)
{
    struct mock_rpc_client *rpc = kzalloc(sizeof(*rpc), GFP_KERNEL);
    if (!rpc)
        return NULL;
    mutex_init(&rpc->lock);
    return rpc;
}

static void mock_rpc_destroy(struct mock_rpc_client *rpc)
{
    if (!rpc)
        return;
    kfree(rpc);
}

static int mock_rpc_send(struct mock_rpc_client *rpc, u32 rpc_type,
                          void *payload, size_t payload_size,
                          void *response, size_t *response_size)
{
    if (!rpc)
        return -EINVAL;

    mutex_lock(&rpc->lock);
    rpc->seq++;
    rpc->pending_seq[rpc->pending_count++] = rpc->seq;
    mutex_unlock(&rpc->lock);

    /* Simulate successful response */
    if (response && response_size) {
        struct gsp_rpc_response *resp = response;
        resp->status = 0;
        resp->rpc_type = rpc_type;
        resp->sequence = rpc->seq;
        *response_size = sizeof(*resp);
    }

    return 0;
}

/* ============================================================
 * Driver Logic Tests with Mocks
 * ============================================================ */

static int test_mock_hardware(void)
{
    struct mock_hw *hw = mock_hw_create();
    TEST_ASSERT(hw != NULL, "Mock HW create");

    /* Test BAR0 write/read */
    mock_hw_write_bar0(hw, 0x1000, 0x1);
    TEST_ASSERT(hw->doorbell_triggered, "Doorbell triggered");
    TEST_ASSERT_EQ(hw->doorbell_count, 1, "Doorbell count");

    u32 val = mock_hw_read_bar0(hw, 0x1000);
    TEST_ASSERT_EQ(val, 0x1, "BAR0 read back");

    /* Test BAR1 write/read */
    mock_hw_write_bar1(hw, 0x1000, 0xDEADBEEFCAFEBABE);
    u64 val64 = mock_hw_read_bar1(hw, 0x1000);
    TEST_ASSERT_EQ(val64, 0xDEADBEEFCAFEBABE, "BAR1 read back");

    mock_hw_destroy(hw);
    return TEST_PASS;
}

static int test_mock_vf_lifecycle(void)
{
    struct mock_vf *vf = mock_vf_create(1, 0x10000000, 0x100000,
                                         0x20000000, 0x100000,
                                         0x30000000, 0x10000);
    TEST_ASSERT(vf != NULL, "Mock VF create");

    TEST_ASSERT(vf->active, "VF active after create");
    TEST_ASSERT_EQ(vf->id, 1, "VF ID");
    TEST_ASSERT_EQ(vf->bar1_offset, 0x10000000, "BAR1 offset");
    TEST_ASSERT_EQ(vf->bar1_size, 0x100000, "BAR1 size");
    TEST_ASSERT_EQ(vf->pt_base, 0x20000000, "Page table base");
    TEST_ASSERT_EQ(vf->pt_size, 0x100000, "Page table size");

    /* Test BAR state */
    TEST_ASSERT_EQ(vf->bar_state.aperture_offset, 0x10000000, "Aperture offset");
    TEST_ASSERT_EQ(vf->bar_state.aperture_size, 0x100000, "Aperture size");
    TEST_ASSERT(!vf->bar_state.force_access, "Force access initially false");

    /* Test WPR list empty */
    TEST_ASSERT(list_empty(&vf->wpr_list), "WPR list empty initially");

    mock_vf_destroy(vf);
    return TEST_PASS;
}

static int test_mock_vf_wpr(void)
{
    struct mock_vf *vf = mock_vf_create(1, 0x10000000, 0x100000,
                                         0x20000000, 0x100000,
                                         0x30000000, 0x10000);
    TEST_ASSERT(vf != NULL, "Mock VF create");

    /* Add WPR region */
    int ret = mock_vf_wpr_add(vf, 0x10000000, 0x10000, 3);
    TEST_ASSERT_EQ(ret, 0, "WPR add");

    ret = mock_vf_wpr_add(vf, 0x20000000, 0x20000, 1);
    TEST_ASSERT_EQ(ret, 0, "WPR add second");

    /* Verify list */
    int count = 0;
    struct mock_wpr_region *rgn;
    mutex_lock(&vf->lock);
    list_for_each_entry(rgn, &vf->wpr_list, list) {
        count++;
    }
    mutex_unlock(&vf->lock);
    TEST_ASSERT_EQ(count, 2, "Two WPR regions");

    /* Remove one */
    ret = mock_vf_wpr_remove(vf, 0x10000000);
    TEST_ASSERT_EQ(ret, 0, "WPR remove");

    count = 0;
    mutex_lock(&vf->lock);
    list_for_each_entry(rgn, &vf->wpr_list, list) {
        count++;
    }
    mutex_unlock(&vf->lock);
    TEST_ASSERT_EQ(count, 1, "One WPR region remaining");

    /* Remove non-existent */
    ret = mock_vf_wpr_remove(vf, 0x30000000);
    TEST_ASSERT_EQ(ret, -ENOENT, "WPR remove non-existent returns ENOENT");

    mock_vf_destroy(vf);
    return TEST_PASS;
}

static int test_mock_rpc_client(void)
{
    struct mock_rpc_client *rpc = mock_rpc_create();
    TEST_ASSERT(rpc != NULL, "Mock RPC create");

    struct gsp_rpc_response resp;
    size_t resp_size = sizeof(resp);
    struct gsp_alloc_payload payload = {
        .size = cpu_to_le64(0x100000),
        .type = cpu_to_le32(GSP_MEM_VRAM),
    };

    int ret = mock_rpc_send(rpc, GSP_RPC_ALLOC, &payload, sizeof(payload), &resp, &resp_size);
    TEST_ASSERT_EQ(ret, 0, "RPC send");

    TEST_ASSERT_EQ(resp.status, 0, "RPC response status");
    TEST_ASSERT_EQ(resp.rpc_type, GSP_RPC_ALLOC, "RPC response type");
    TEST_ASSERT_EQ(resp.sequence, 1, "RPC response sequence");

    /* Second call */
    ret = mock_rpc_send(rpc, GSP_RPC_PIN, &payload, sizeof(payload), &resp, &resp_size);
    TEST_ASSERT_EQ(ret, 0, "RPC send second");
    TEST_ASSERT_EQ(resp.sequence, 2, "RPC response sequence 2");

    mock_rpc_destroy(rpc);
    return TEST_PASS;
}

static int test_driver_vf_creation_logic(void)
{
    /* Simulate driver VF creation logic */
    struct mock_hw *hw = mock_hw_create();
    struct mock_rpc_client *rpc = mock_rpc_create();
    struct mock_vf *vfs[8] = {0};

    /* Create VFs 1-4 */
    for (int i = 1; i <= 4; i++) {
        vfs[i] = mock_vf_create(i, 0x10000000 * i, 0x100000,
                                 0x20000000 * i, 0x100000,
                                 0x30000000 * i, 0x10000);
        TEST_ASSERT(vfs[i] != NULL, "VF creation in loop");
        TEST_ASSERT(vfs[i]->active, "VF active in loop");
    }

    /* Initialize BAR for each VF */
    for (int i = 1; i <= 4; i++) {
        vfs[i]->bar_state.aperture_offset = vfs[i]->bar1_offset;
        vfs[i]->bar_state.aperture_size = vfs[i]->bar1_size;
        TEST_ASSERT_EQ(vfs[i]->bar_state.aperture_offset, 0x10000000 * i, "VF BAR offset");
        TEST_ASSERT_EQ(vfs[i]->bar_state.aperture_size, 0x100000, "VF BAR size");
    }

    /* Add WPR for each VF */
    for (int i = 1; i <= 4; i++) {
        int ret = mock_vf_wpr_add(vfs[i], vfs[i]->pt_base, vfs[i]->pt_size, 3);
        TEST_ASSERT_EQ(ret, 0, "VF WPR add in loop");
    }

    /* Simulate RPC calls for each VF */
    for (int i = 1; i <= 4; i++) {
        struct gsp_rpc_response resp;
        size_t resp_size = sizeof(resp);
        struct gsp_alloc_payload payload = {
            .size = cpu_to_le64(0x100000),
            .type = cpu_to_le32(GSP_MEM_VRAM),
            .vf_id = cpu_to_le32(i),
        };
        int ret = mock_rpc_send(rpc, GSP_RPC_ALLOC, &payload, sizeof(payload), &resp, &resp_size);
        TEST_ASSERT_EQ(ret, 0, "VF RPC alloc");
        TEST_ASSERT_EQ(resp.status, 0, "VF RPC response OK");
    }

    /* Cleanup */
    for (int i = 1; i <= 4; i++) {
        mock_vf_destroy(vfs[i]);
    }
    mock_rpc_destroy(rpc);
    mock_hw_destroy(hw);

    return TEST_PASS;
}

static int test_migration_progress_tracking(void)
{
    struct {
        u64 pages_transferred;
        u64 bytes_transferred;
        u64 dirty_pages;
        u64 *page_list;
        u32 page_count;
    } progress = {0};

    progress.page_count = 1000;
    progress.page_list = kcalloc(progress.page_count, sizeof(u64), GFP_KERNEL);
    TEST_ASSERT(progress.page_list != NULL, "Progress page list alloc");

    /* Simulate transfer loop */
    for (int iter = 0; iter < 10; iter++) {
        progress.pages_transferred += 100;
        progress.bytes_transferred += 100 * 4096;
        progress.dirty_pages = 50 - (iter * 5);

        TEST_ASSERT(progress.pages_transferred <= 1000, "Pages not exceeded");
        TEST_ASSERT(progress.bytes_transferred <= 1000 * 4096, "Bytes not exceeded");
    }

    TEST_ASSERT_EQ(progress.pages_transferred, 1000, "Final pages");
    TEST_ASSERT_EQ(progress.bytes_transferred, 1000 * 4096, "Final bytes");
    TEST_ASSERT_EQ(progress.dirty_pages, 0, "Final dirty pages");

    kfree(progress.page_list);
    return TEST_PASS;
}

static int test_bar_state_machine(void)
{
    struct {
        u64 aperture_offset;
        u64 aperture_size;
        bool force_access;
        u32 force_vf;
    } bar_state = {0};

    /* Initial state */
    bar_state.aperture_offset = 0x10000000;
    bar_state.aperture_size = 0x100000;
    TEST_ASSERT_EQ(bar_state.aperture_offset, 0x10000000, "Initial aperture offset");
    TEST_ASSERT(!bar_state.force_access, "Force access initially false");

    /* Enable force access */
    bar_state.force_access = true;
    bar_state.force_vf = 1;
    TEST_ASSERT(bar_state.force_access, "Force access enabled");
    TEST_ASSERT_EQ(bar_state.force_vf, 1, "Force VF set");

    /* Disable force access */
    bar_state.force_access = false;
    bar_state.force_vf = 0;
    TEST_ASSERT(!bar_state.force_access, "Force access disabled");
    TEST_ASSERT_EQ(bar_state.force_vf, 0, "Force VF cleared");

    return TEST_PASS;
}

static int test_concurrent_vf_operations(void)
{
    struct mock_vf *vf1 = mock_vf_create(1, 0x10000000, 0x100000, 0x20000000, 0x100000, 0x30000000, 0x10000);
    struct mock_vf *vf2 = mock_vf_create(2, 0x20000000, 0x100000, 0x40000000, 0x100000, 0x60000000, 0x10000);
    struct mock_rpc_client *rpc = mock_rpc_create();

    TEST_ASSERT(vf1 && vf2 && rpc, "Create two VFs and RPC");

    /* Simulate concurrent operations */
    struct gsp_rpc_response resp;
    size_t resp_size = sizeof(resp);

    /* VF1 alloc */
    struct gsp_alloc_payload payload1 = {
        .size = cpu_to_le64(0x100000),
        .type = cpu_to_le32(GSP_MEM_VRAM),
        .vf_id = cpu_to_le32(1),
    };
    int ret = mock_rpc_send(rpc, GSP_RPC_ALLOC, &payload1, sizeof(payload1), &resp, &resp_size);
    TEST_ASSERT_EQ(ret, 0, "VF1 alloc");
    TEST_ASSERT_EQ(resp.status, 0, "VF1 alloc response");

    /* VF2 alloc */
    struct gsp_alloc_payload payload2 = {
        .size = cpu_to_le64(0x200000),
        .type = cpu_to_le32(GSP_MEM_VRAM),
        .vf_id = cpu_to_le32(2),
    };
    ret = mock_rpc_send(rpc, GSP_RPC_ALLOC, &payload2, sizeof(payload2), &resp, &resp_size);
    TEST_ASSERT_EQ(ret, 0, "VF2 alloc");
    TEST_ASSERT_EQ(resp.status, 0, "VF2 alloc response");

    /* VF1 pin */
    struct gsp_pin_payload pin_payload = {
        .handle = cpu_to_le64(0x1000),
        .vf_id = cpu_to_le32(1),
    };
    ret = mock_rpc_send(rpc, GSP_RPC_PIN, &pin_payload, sizeof(pin_payload), &resp, &resp_size);
    TEST_ASSERT_EQ(ret, 0, "VF1 pin");

    /* VF2 BAR trap */
    struct gsp_bar_trap_payload bar_payload = {
        .vf_id = cpu_to_le32(2),
        .bar_index = cpu_to_le32(1),
    };
    ret = mock_rpc_send(rpc, GSP_RPC_BAR_TRAP, &bar_payload, sizeof(bar_payload), &resp, &resp_size);
    TEST_ASSERT_EQ(ret, 0, "VF2 BAR trap");

    /* Verify sequence numbers */
    TEST_ASSERT_EQ(resp.sequence, 4, "Sequence number 4");

    mock_vf_destroy(vf1);
    mock_vf_destroy(vf2);
    mock_rpc_destroy(rpc);

    return TEST_PASS;
}

/* ============================================================
 * Module Init/Exit
 * ============================================================ */

static int __init gsp_mock_test_init(void)
{
    pr_info("========================================\n");
    pr_info("GSP vGPU-IO Mock Driver Test Suite\n");
    pr_info("========================================\n");

    test_mock_hardware();
    test_mock_vf_lifecycle();
    test_mock_vf_wpr();
    test_mock_rpc_client();
    test_driver_vf_creation_logic();
    test_migration_progress_tracking();
    test_bar_state_machine();
    test_concurrent_vf_operations();

    pr_info("========================================\n");
    pr_info("Mock Test Results: %d total, %d passed, %d failed\n",
            test_count, pass_count, fail_count);
    pr_info("========================================\n");

    if (fail_count > 0) {
        pr_err("MOCK TEST SUITE FAILED\n");
        return -EINVAL;
    }

    pr_info("MOCK TEST SUITE PASSED\n");
    return 0;
}

static void __exit gsp_mock_test_exit(void)
{
    pr_info("GSP vGPU-IO Mock Test Suite Exited\n");
}

module_init(gsp_mock_test_init);
module_exit(gsp_mock_test_exit);

MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Open-IOV Project");
MODULE_DESCRIPTION("GSP vGPU-IO Mock Driver Test");
MODULE_VERSION("1.0");