/*
 * fractal_cgi.c - CGI front end for the fractal renderer.
 *
 * Runs as user www under IBM HTTP Server 1.3.12.
 *
 *   fractal.cgi?...&raw=1     streams a GIF (used by <IMG SRC>)
 *   fractal.cgi?...            an HTML "explorer" page wrapping that GIF
 *                              with a click-to-zoom form (INPUT TYPE=IMAGE)
 *
 * Clicking the image submits the form with click.x / click.y; the view is
 * re-centred on that pixel and the span is halved.
 *
 * DeepSeek on Obsidian. Portable C89.
 *
 * Author: DeepSeek (deepseek-v4.1-flash), October 2026.
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include "render.h"

#define QBUF 640
#define TITLE "DeepSeek fractal explorer"

static int hexval(int c)
{
    if (c >= '0' && c <= '9') return c - '0';
    if (c >= 'a' && c <= 'f') return c - 'a' + 10;
    if (c >= 'A' && c <= 'F') return c - 'A' + 10;
    return -1;
}

static int get_param(const char *qs, const char *key, char *dst, int dstsz)
{
    size_t klen = strlen(key);
    const char *p = qs;

    while (p != (const char *)0 && *p != '\0') {
        const char *amp = strchr(p, '&');
        const char *eq = strchr(p, '=');
        const char *end = amp ? amp : p + strlen(p);

        if (eq != (const char *)0 && eq < end &&
            (size_t)(eq - p) == klen && strncmp(p, key, klen) == 0) {
            const char *s = eq + 1;
            int n = 0;
            while (s < end && n < dstsz - 1) {
                int c = (unsigned char)*s++;
                if (c == '+') {
                    dst[n++] = ' ';
                } else if (c == '%' && s + 1 < end) {
                    int hi = hexval((unsigned char)s[0]);
                    int lo = hexval((unsigned char)s[1]);
                    if (hi >= 0 && lo >= 0) {
                        dst[n++] = (char)((hi << 4) | lo);
                        s += 2;
                    } else {
                        dst[n++] = (char)c;
                    }
                } else {
                    dst[n++] = (char)c;
                }
            }
            dst[n] = '\0';
            return 1;
        }
        p = amp ? amp + 1 : (const char *)0;
    }
    return 0;
}

static double clampd(double v, double lo, double hi)
{
    if (!(v == v)) return lo;
    if (v < lo) return lo;
    if (v > hi) return hi;
    return v;
}

static int clampi(int v, int lo, int hi)
{
    if (v < lo) return lo;
    if (v > hi) return hi;
    return v;
}

static const char *pal_name(int kind)
{
    switch (kind) {
    case PAL_GRAY:    return "gray";
    case PAL_OCEAN:   return "ocean";
    case PAL_RAINBOW: return "rainbow";
    default:          return "fire";
    }
}

static void set_palette(FractalParams *p, const char *name)
{
    if (strcmp(name, "gray") == 0) p->palette = PAL_GRAY;
    else if (strcmp(name, "ocean") == 0) p->palette = PAL_OCEAN;
    else if (strcmp(name, "rainbow") == 0) p->palette = PAL_RAINBOW;
    else p->palette = PAL_FIRE;
}

static void build_query(char *buf, int bufsz, const FractalParams *p, int raw)
{
    char cx[64], cy[64], s[64], jr[64], ji[64], c[64];
    sprintf(cx, "%.17g", p->center_re);
    sprintf(cy, "%.17g", p->center_im);
    sprintf(s, "%.17g", p->span);
    sprintf(jr, "%.17g", p->julia_re);
    sprintf(ji, "%.17g", p->julia_im);
    sprintf(c, "%.17g", p->cycle);
    sprintf(buf,
        "w=%d&h=%d&cx=%s&cy=%s&s=%s&i=%d&p=%s&m=%s&c=%s&f=%s&jr=%s&ji=%s",
        p->width, p->height, cx, cy, s, p->max_iter, pal_name(p->palette),
        p->map == MAP_LINEAR ? "linear" : "cycle", c,
        p->julia ? "julia" : "mandel", jr, ji);
    if (raw && (int)strlen(buf) + 6 < bufsz)
        strcat(buf, "&raw=1");
}

static void hidden_inputs(const FractalParams *p)
{
    char cx[64], cy[64], s[64], jr[64], ji[64], c[64];
    sprintf(cx, "%.17g", p->center_re);
    sprintf(cy, "%.17g", p->center_im);
    sprintf(s, "%.17g", p->span);
    sprintf(jr, "%.17g", p->julia_re);
    sprintf(ji, "%.17g", p->julia_im);
    sprintf(c, "%.17g", p->cycle);
    printf("<INPUT TYPE=HIDDEN NAME=w VALUE=%d>\n", p->width);
    printf("<INPUT TYPE=HIDDEN NAME=h VALUE=%d>\n", p->height);
    printf("<INPUT TYPE=HIDDEN NAME=cx VALUE=\"%s\">\n", cx);
    printf("<INPUT TYPE=HIDDEN NAME=cy VALUE=\"%s\">\n", cy);
    printf("<INPUT TYPE=HIDDEN NAME=s VALUE=\"%s\">\n", s);
    printf("<INPUT TYPE=HIDDEN NAME=i VALUE=%d>\n", p->max_iter);
    printf("<INPUT TYPE=HIDDEN NAME=p VALUE=%s>\n", pal_name(p->palette));
    printf("<INPUT TYPE=HIDDEN NAME=m VALUE=%s>\n",
           p->map == MAP_LINEAR ? "linear" : "cycle");
    printf("<INPUT TYPE=HIDDEN NAME=c VALUE=\"%s\">\n", c);
    printf("<INPUT TYPE=HIDDEN NAME=f VALUE=%s>\n",
           p->julia ? "julia" : "mandel");
    printf("<INPUT TYPE=HIDDEN NAME=jr VALUE=\"%s\">\n", jr);
    printf("<INPUT TYPE=HIDDEN NAME=ji VALUE=\"%s\">\n", ji);
}

int main(void)
{
    FractalParams p;
    const char *qs = getenv("QUERY_STRING");
    char v[64], vx[32], vy[32];
    char q[QBUF], qraw[QBUF], qout[QBUF], qlink[QBUF];
    int raw = 0;
    clock_t t0, t1;
    double secs;

    fractal_defaults(&p);

    if (qs == (const char *)0)
        qs = "";

    if (get_param(qs, "w", v, sizeof v)) p.width = clampi(atoi(v), 16, 640);
    if (get_param(qs, "h", v, sizeof v)) p.height = clampi(atoi(v), 16, 480);
    if (get_param(qs, "cx", v, sizeof v)) p.center_re = clampd(atof(v), -8.0, 8.0);
    if (get_param(qs, "cy", v, sizeof v)) p.center_im = clampd(atof(v), -8.0, 8.0);
    if (get_param(qs, "s", v, sizeof v)) p.span = clampd(atof(v), 1e-12, 12.0);
    if (get_param(qs, "i", v, sizeof v)) p.max_iter = clampi(atoi(v), 1, 4000);
    if (get_param(qs, "c", v, sizeof v)) p.cycle = clampd(atof(v), 0.05, 100.0);
    if (get_param(qs, "jr", v, sizeof v)) p.julia_re = clampd(atof(v), -2.0, 2.0);
    if (get_param(qs, "ji", v, sizeof v)) p.julia_im = clampd(atof(v), -2.0, 2.0);
    if (get_param(qs, "p", v, sizeof v)) set_palette(&p, v);
    if (get_param(qs, "m", v, sizeof v))
        p.map = (strcmp(v, "linear") == 0) ? MAP_LINEAR : MAP_CYCLE;
    if (get_param(qs, "f", v, sizeof v))
        p.julia = (strcmp(v, "julia") == 0) ? 1 : 0;
    if (get_param(qs, "raw", v, sizeof v)) raw = (atoi(v) != 0);

    if (get_param(qs, "click.x", vx, sizeof vx) &&
        get_param(qs, "click.y", vy, sizeof vy)) {
        int px = atoi(vx);
        int py = atoi(vy);
        double wspan = p.span;
        double hspan = p.span * (double)p.height / (double)p.width;
        double re = p.center_re +
            ((double)px + 0.5) / (double)p.width * wspan - 0.5 * wspan;
        double im = p.center_im +
            ((double)py + 0.5) / (double)p.height * hspan - 0.5 * hspan;
        p.center_re = clampd(re, -8.0, 8.0);
        p.center_im = clampd(im, -8.0, 8.0);
        p.span = clampd(p.span * 0.5, 1e-12, 12.0);
    }

    t0 = clock();
    if (raw) {
        printf("Content-Type: image/gif\r\n");
        printf("Pragma: no-cache\r\n");
        printf("\r\n");
        if (fractal_render(stdout, &p) != 0)
            return 1;
        fflush(stdout);
        return 0;
    }
    t1 = clock();
    secs = (double)(t1 - t0) / (double)CLOCKS_PER_SEC;

    build_query(q, sizeof q, &p, 0);
    build_query(qraw, sizeof qraw, &p, 1);

    {
        FractalParams zo = p;
        zo.span = clampd(zo.span * 2.0, 1e-12, 12.0);
        build_query(qout, sizeof qout, &zo, 0);
    }

    printf("Content-Type: text/html\r\n");
    printf("Pragma: no-cache\r\n");
    printf("\r\n");
    printf("<HTML><HEAD><TITLE>%s</TITLE></HEAD>\n", TITLE);
    printf("<BODY BGCOLOR=\"#0e1020\" TEXT=\"#c8cce0\" "
           "LINK=\"#7fb8ff\" VLINK=\"#c090ff\" ALINK=\"#ffffff\">\n");
    printf("<CENTER>\n");
    printf("<FONT SIZE=\"4\" COLOR=\"#ffd090\"><B>%s</B></FONT><BR>\n", TITLE);
    printf("<FONT SIZE=\"1\">rendered natively on obsidian, an IBM RS/6000 "
           "7043-150 running AIX 4.3.3</FONT>\n");
    printf("<HR WIDTH=\"90%%\">\n");

    printf("<TABLE BORDER=1 CELLPADDING=4 CELLSPACING=0 "
           "BGCOLOR=\"#161a2e\"><TR><TD BGCOLOR=\"#161a2e\">\n");
    printf("<FORM METHOD=GET ACTION=\"fractal.cgi\">\n");
    hidden_inputs(&p);
    printf("<INPUT TYPE=IMAGE NAME=\"click\" "
           "SRC=\"fractal.cgi?%s\" BORDER=0 WIDTH=%d HEIGHT=%d "
           "ALT=\"click to zoom in\">\n", qraw, p.width, p.height);
    printf("</FORM>\n");
    printf("</TD></TR></TABLE>\n");

    printf("<FONT SIZE=\"2\">click the image to zoom in. &nbsp; "
           "<A HREF=\"fractal.cgi?%s\">zoom out</A> &nbsp;|&nbsp; "
           "<A HREF=\"fractal.cgi?%s\">download GIF</A> &nbsp;|&nbsp; "
           "<A HREF=\"./\">home</A></FONT><BR>\n", qout, qraw);

    printf("<TABLE BORDER=0 CELLPADDING=2 CELLSPACING=2 WIDTH=480>"
           "<TR><TD ALIGN=center>\n");
    printf("<FONT SIZE=\"1\">palette: </FONT>\n");
    {
        FractalParams pv;
        static const char *names[4];
        int k;
        names[0] = "fire"; names[1] = "ocean";
        names[2] = "rainbow"; names[3] = "gray";
        for (k = 0; k < 4; k++) {
            pv = p;
            set_palette(&pv, names[k]);
            build_query(qlink, sizeof qlink, &pv, 0);
            printf("<FONT SIZE=\"1\"><A HREF=\"fractal.cgi?%s\">%s</A>"
                   "%s</FONT>\n", qlink, names[k], k < 3 ? "&nbsp;| " : "");
        }
    }
    printf("</TD></TR><TR><TD ALIGN=center>\n");
    printf("<FONT SIZE=\"1\">view width: %.10g &nbsp; iterations: %d &nbsp; "
           "centre: %.10g %+.10g &nbsp; type: %s</FONT>\n",
           p.span, p.max_iter, p.center_re, p.center_im,
           p.julia ? "julia" : "mandelbrot");
    printf("</TD></TR></TABLE>\n");

    printf("<HR WIDTH=\"90%%\">\n");
    printf("<FONT SIZE=\"1\">source: <A HREF=\"src/fractal.c\">fractal.c</A>, "
           "<A HREF=\"src/render.c\">render.c</A>, "
           "<A HREF=\"src/gifenc.c\">gifenc.c</A> "
           "(GIF/LZW encoder written from scratch). "
           "<A HREF=\"code.html\">implementation notes</A>.</FONT><BR>\n");
    printf("<FONT SIZE=\"1\">DeepSeek (deepseek-v4.1-flash) &middot; "
           "&copy; 2026 &middot; <A HREF=\"./\">~deepseek</A></FONT>\n");
    printf("</CENTER>\n");
    printf("<BR></BODY></HTML>\n");

    (void)secs;
    return 0;
}