// ============================================================================
// demo.c - Demonstration of using Windows 3.x display drivers from DOS
//
// This program loads a Windows 3.x accelerated display driver (.DRV file)
// and uses its hardware-accelerated functions to draw on screen.
//
// Usage: demo [-d] <driver.drv>
//   -d    Enable debug output
//
// Example:
//   demo vga.drv
//   demo -d s3trio.drv
// ============================================================================

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>
#include <pc.h>
#include <dpmi.h>

#include "win31drv/windrv.h"
#include "win31drv/wintypes.h"
#include "win31drv/log.h"

__attribute__((noinline))
static void demoDrawing(WdrvHandleT drv);
static void printDriverInfo(WdrvHandleT drv);
static void printUsage(const char *progName);
static void setupPalette(WdrvHandleT drv);


int main(int argc, char *argv[])
{
    const char *driverPath = NULL;
    bool        debug      = false;

    // Parse arguments
    for (int i = 1; i < argc; i++) {
        if (strcmp(argv[i], "-d") == 0) {
            debug = true;
        } else if (argv[i][0] != '-') {
            driverPath = argv[i];
        } else {
            printUsage(argv[0]);
            return 1;
        }
    }

    if (!driverPath) {
        printUsage(argv[0]);
        return 1;
    }

    logInit("OUTPUT.LOG");

    // Initialize the library
    logMsg("Initializing windrv library...\n");
    int32_t err = wdrvInit();
    if (err != WDRV_OK) {
        logErr("Failed to initialize: %s\n", wdrvGetLastErrorString());
        return 1;
    }

    if (debug) {
        wdrvSetDebug(true);
    }

    // Load the driver
    logMsg("Loading driver: %s\n", driverPath);
    WdrvHandleT drv = wdrvLoadDriver(driverPath);
    if (!drv) {
        logErr("Failed to load driver: %s\n", wdrvGetLastErrorString());
        wdrvShutdown();
        return 1;
    }

    // Print driver info
    printDriverInfo(drv);

    // Redirect stdout to the log file before entering SVGA mode.
    // In graphics mode, console output through INT 21h can crash
    // because the console handler tries to access VGA text memory
    // that's now part of the SVGA framebuffer.
    freopen("OUTPUT.LOG", "a", stdout);

    // Enable the driver (set video mode)
    logMsg("Enabling driver...\n");
    err = wdrvEnable(drv, 0, 0, 0); // Use driver defaults
    if (err != WDRV_OK) {
        logErr("Failed to enable driver: %s\n", wdrvGetLastErrorString());
        wdrvUnloadDriver(drv);
        wdrvShutdown();
        return 1;
    }

    // Set up a 256-color palette via the driver's SetPalette DDI.
    // This updates both the driver's internal color table (used by
    // RealizeObject for color matching) and the VGA DAC hardware.
    setupPalette(drv);

    // Run drawing demos
    demoDrawing(drv);

    logMsg("Drawing complete. Press any key...\n");

    // Wait for a keypress so we can see the output
    while (!kbhit()) {
        // Busy-wait; kbhit() does keyboard I/O which keeps DOSBox-X responsive
    }
    (void)getkey(); // consume the key

    // Disable the driver (restore text mode)
    logMsg("Calling wdrvDisable...\n");
    err = wdrvDisable(drv);
    if (err != WDRV_OK) {
        logMsg("wdrvDisable failed (err=%d), forcing text mode via INT 10h\n", (int)err);
        __dpmi_regs dr;
        memset(&dr, 0, sizeof(dr));
        dr.x.ax = 0x0003; // INT 10h AH=00 AL=03: set 80x25 text mode
        __dpmi_int(0x10, &dr);
    }

    // Clean up
    logMsg("Unloading driver...\n");
    wdrvUnloadDriver(drv);
    wdrvShutdown();

    logMsg("Done.\n");
    logShutdown();
    return 0;
}


static void printUsage(const char *progName)
{
    logErr("Usage: %s [-d] <driver.drv>\n", progName);
    logErr("  -d    Enable debug output\n");
    logErr("\nLoads a Windows 3.x display driver and demonstrates\n");
    logErr("its accelerated drawing functions from DOS.\n");
}


static void printDriverInfo(WdrvHandleT drv)
{
    WdrvInfoT info;
    wdrvGetInfo(drv, &info);

    logMsg("\n=== Driver Information ===\n");
    logMsg("  Name:          %s\n", info.driverName);
    logMsg("  Version:       %u.%u\n", info.driverVersion >> 8,
           info.driverVersion & 0xFF);
    logMsg("  Resolution:    %" PRId32 "x%" PRId32 "\n", info.maxWidth, info.maxHeight);
    logMsg("  Color depth:   %" PRId32 " bpp\n", info.maxBpp);
    logMsg("  Colors:        %" PRId32 "\n", info.numColors);
    logMsg("  Raster caps:   0x%04" PRIX32 "\n", info.rasterCaps);
    logMsg("  Capabilities:\n");
    logMsg("    BitBlt:      %s\n", info.hasBitBlt ? "yes" : "no");
    logMsg("    Output:      %s\n", info.hasOutput ? "yes" : "no");
    logMsg("    Pixel:       %s\n", info.hasPixel ? "yes" : "no");
    logMsg("    StretchBlt:  %s\n", info.hasStretchBlt ? "yes" : "no");
    logMsg("    ExtTextOut:  %s\n", info.hasExtTextOut ? "yes" : "no");
    logMsg("    SetPalette:  %s\n", info.hasSetPalette ? "yes" : "no");
    logMsg("    SetCursor:   %s\n", info.hasSetCursor ? "yes" : "no");
}


// noinline: when inlined into main with -O2, the optimizer mishandles
// callee-saved registers across the thunk calls in the Demo 2 → Demo 3
// transition, causing the handle pointer to be corrupted.
__attribute__((noinline))
static void demoDrawing(WdrvHandleT drv)
{
    WdrvInfoT info;
    wdrvGetInfo(drv, &info);

    int16_t screenW = (int16_t)info.maxWidth;
    int16_t screenH = (int16_t)info.maxHeight;

    if (screenW == 0) {
        screenW = 640;
    }
    if (screenH == 0) {
        screenH = 480;
    }

    logMsg("demoDrawing: screenW=%d screenH=%d hasBitBlt=%d hasOutput=%d hasPixel=%d\n",
           screenW, screenH, info.hasBitBlt, info.hasOutput, info.hasPixel);

    // Demo 1: Fill rectangles
    if (info.hasBitBlt) {
        logMsg("Demo 1: Fill rectangles\n");

        // Clear screen to white
        wdrvFillRect(drv, 0, 0, screenW, screenH, MAKE_RGB(255, 255, 255));

        static const uint32_t vgaColors[] = {
            MAKE_RGB(  0,   0,   0), // black
            MAKE_RGB(  0,   0, 255), // blue
            MAKE_RGB(  0, 255,   0), // green
            MAKE_RGB(  0, 255, 255), // cyan
            MAKE_RGB(255,   0,   0), // red
            MAKE_RGB(255,   0, 255), // magenta
            MAKE_RGB(255, 255,   0), // yellow
            MAKE_RGB(170, 170, 170), // light gray
            MAKE_RGB( 85,  85,  85), // dark gray
            MAKE_RGB( 85,  85, 255), // light blue
            MAKE_RGB( 85, 255,  85), // light green
            MAKE_RGB( 85, 255, 255), // light cyan
            MAKE_RGB(255,  85,  85), // light red
            MAKE_RGB(255,  85, 255), // light magenta
            MAKE_RGB(255, 255,  85), // yellow-ish
            MAKE_RGB(128, 128, 128), // mid gray
        };

        int16_t boxW = screenW / 4;
        int16_t boxH = screenH / 4;

        for (int16_t row = 0; row < 4; row++) {
            for (int16_t col = 0; col < 4; col++) {
                int idx = row * 4 + col;
                wdrvFillRect(drv, col * boxW + 4, row * boxH + 4,
                             boxW - 8, boxH - 8, vgaColors[idx]);
            }
        }

        logMsg("  Drew %d colored rectangles\n", 16);
    }

    // Demo 2: Draw pixel patterns
    if (info.hasPixel) {
        logMsg("Demo 2: Pixel patterns (8x8)\n");
        int pixCount = 0;
        for (int16_t y = 0; y < 8 && y < screenH; y++) {
            for (int16_t x = 0; x < 8 && x < screenW; x++) {
                uint8_t r = (uint8_t)(x * 32);
                uint8_t g = (uint8_t)(y * 32);
                uint8_t b = (uint8_t)((x + y) * 16);
                wdrvSetPixel(drv, x + screenW - 18, y + 10, MAKE_RGB(r, g, b));
                pixCount++;
            }
        }
        logMsg("  Drew %d pixels\n", pixCount);
    }

    // Demo 3: Draw lines using Output (polyline with realized pen)
    if (info.hasOutput) {
        logMsg("Demo 3: Lines (starburst)\n");

        int16_t cx = screenW / 2;
        int16_t cy = screenH / 2;
        int16_t radius = (screenH < screenW ? screenH : screenW) / 3;
        int     lineCount = 0;

        for (int angle = 0; angle < 360; angle += 15) {
            int32_t dx = 0;
            int32_t dy = 0;

            int a  = angle % 360;
            int qa = a % 90;
            int32_t s = (int32_t)qa * radius / 90;
            int32_t c = (int32_t)(90 - qa) * radius / 90;

            if (a < 90) {
                dx = s;
                dy = -c;
            } else if (a < 180) {
                dx = c;
                dy = s;
            } else if (a < 270) {
                dx = -s;
                dy = c;
            } else {
                dx = -c;
                dy = -s;
            }

            Point16T pts[2];
            pts[0].x = cx;
            pts[0].y = cy;
            pts[1].x = (int16_t)(cx + dx);
            pts[1].y = (int16_t)(cy + dy);

            uint32_t lineColor = MAKE_RGB(
                (uint8_t)(angle * 255 / 360),
                (uint8_t)(255 - angle * 255 / 360),
                128);

            wdrvPolyline(drv, pts, 2, lineColor);
            lineCount++;
        }
        logMsg("  Drew %d lines\n", lineCount);
    }

    // Demo 4: Screen-to-screen blit test
    if (info.hasBitBlt) {
        logMsg("Demo 4: Screen-to-screen blit\n");

        WdrvBitBltParamsT bp;
        memset(&bp, 0, sizeof(bp));
        bp.srcX   = 0;
        bp.srcY   = 0;
        bp.dstX   = screenW / 2;
        bp.dstY   = screenH / 2;
        bp.width  = screenW / 4;
        bp.height = screenH / 4;
        bp.rop3   = SRCCOPY;
        wdrvBitBlt(drv, &bp);
        logMsg("  Screen blit done\n");
    }

    // Demo 5: Text output using ExtTextOut
    if (info.hasExtTextOut) {
        logMsg("Demo 5: ExtTextOut text rendering\n");
        int32_t ret;

        // Opaque text: white on blue (built-in font via NULL)
        const char *msg1 = "Hello from ExtTextOut!";
        ret = wdrvExtTextOut(drv, 10, 10, msg1, (int16_t)strlen(msg1),
                             MAKE_RGB(255, 255, 255), MAKE_RGB(0, 0, 170), true, NULL);
        logMsg("  msg1 ret=%" PRId32 "\n", ret);

        // Opaque text: yellow on dark red
        const char *msg2 = "Win3.x DDI Text Output";
        ret = wdrvExtTextOut(drv, 10, 30, msg2, (int16_t)strlen(msg2),
                             MAKE_RGB(255, 255, 0), MAKE_RGB(170, 0, 0), true, NULL);
        logMsg("  msg2 ret=%" PRId32 "\n", ret);

        // Transparent text: green on existing background
        const char *msg3 = "Transparent mode";
        ret = wdrvExtTextOut(drv, 10, 50, msg3, (int16_t)strlen(msg3),
                             MAKE_RGB(0, 255, 0), MAKE_RGB(0, 0, 0), false, NULL);
        logMsg("  msg3 ret=%" PRId32 "\n", ret);

        // Show resolution info
        char buf[64];
        int len = sprintf(buf, "Mode: %dx%d", screenW, screenH);
        ret = wdrvExtTextOut(drv, 10, 70, buf, (int16_t)len,
                             MAKE_RGB(255, 255, 255), MAKE_RGB(0, 0, 0), true, NULL);
        logMsg("  msg4 ret=%" PRId32 "\n", ret);

        logMsg("  Text output done\n");
    }

    // Demo 6: Multiple loaded fonts
    if (info.hasExtTextOut) {
        logMsg("Demo 6: Loaded fonts from .FON files\n");
        int32_t ret;

        // Load fonts from .FON files
        WdrvFontT courFont = wdrvLoadFontFon("COURE.FON", 1);   // 9x16 Courier
        WdrvFontT sansFont = wdrvLoadFontFon("SSERIFE.FON", 0); // MS Sans Serif
        WdrvFontT sysFont  = wdrvLoadFontFon("VGASYS.FON", 0);  // System

        int16_t textY = 100;

        if (courFont) {
            const char *msg = "Courier: The quick brown fox jumps over the lazy dog";
            ret = wdrvExtTextOut(drv, 10, textY, msg, (int16_t)strlen(msg),
                                 MAKE_RGB(255, 255, 255), MAKE_RGB(0, 0, 128), true, courFont);
            logMsg("  Courier ret=%" PRId32 "\n", ret);
            textY += 20;
        } else {
            logMsg("  COURE.FON not loaded\n");
        }

        if (sansFont) {
            const char *msg = "Sans Serif: The quick brown fox jumps over the lazy dog";
            ret = wdrvExtTextOut(drv, 10, textY, msg, (int16_t)strlen(msg),
                                 MAKE_RGB(255, 255, 0), MAKE_RGB(128, 0, 0), true, sansFont);
            logMsg("  Sans ret=%" PRId32 "\n", ret);
            textY += 20;
        } else {
            logMsg("  SSERIFE.FON not loaded\n");
        }

        if (sysFont) {
            const char *msg = "System: The quick brown fox jumps over the lazy dog";
            ret = wdrvExtTextOut(drv, 10, textY, msg, (int16_t)strlen(msg),
                                 MAKE_RGB(0, 255, 255), MAKE_RGB(0, 0, 0), true, sysFont);
            logMsg("  System ret=%" PRId32 "\n", ret);
            textY += 20;
        } else {
            logMsg("  VGASYS.FON not loaded\n");
        }

        // Built-in font for comparison
        const char *msg = "Built-in: The quick brown fox jumps over the lazy dog";
        ret = wdrvExtTextOut(drv, 10, textY, msg, (int16_t)strlen(msg),
                             MAKE_RGB(255, 255, 255), MAKE_RGB(0, 128, 0), true, NULL);
        logMsg("  Built-in ret=%" PRId32 "\n", ret);

        wdrvUnloadFont(courFont);
        wdrvUnloadFont(sansFont);
        wdrvUnloadFont(sysFont);
        logMsg("  Font demo done\n");
    }
}


static void setupPalette(WdrvHandleT drv)
{
    // The driver sets up its own palette during Enable (via VBE 4F09)
    // and stores an internal color table that RealizeObject uses for
    // color matching. We leave the palette as-is so the DAC and the
    // internal table stay in sync. RealizeObject will find the best
    // matching index, and the DAC will display the correct color.
    (void)drv;
}