/*
 * libbsdl - JSON serialization (the optional output layer essim consumes).
 * SPDX-License-Identifier: LGPL-2.1-or-later
 *
 * Self-contained: a tiny growable string buffer, no external JSON dependency.
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "bsdl/bsdl.h"

/* ---- growable string buffer ---- */
typedef struct {
    char*  buf;
    size_t len;
    size_t cap;
    int    oom;   /* sticky out-of-memory flag */
} sb_t;

static void sb_reserve(sb_t* sb, size_t extra)
{
    size_t need;
    char*  p;
    if (sb->oom)
        return;
    need = sb->len + extra + 1;
    if (need <= sb->cap)
        return;
    while (sb->cap < need)
        sb->cap = sb->cap ? sb->cap * 2 : 256;
    p = (char*)realloc(sb->buf, sb->cap);
    if (!p) { sb->oom = 1; return; }
    sb->buf = p;
}

static void sb_putc(sb_t* sb, char c)
{
    sb_reserve(sb, 1);
    if (sb->oom) return;
    sb->buf[sb->len++] = c;
}

static void sb_puts(sb_t* sb, const char* s)
{
    size_t n;
    if (!s) s = "";
    n = strlen(s);
    sb_reserve(sb, n);
    if (sb->oom) return;
    memcpy(sb->buf + sb->len, s, n);
    sb->len += n;
}

/* Append a JSON string literal (with quotes) for `s`, or `null` if s == NULL. */
static void sb_json_str(sb_t* sb, const char* s)
{
    if (!s) { sb_puts(sb, "null"); return; }
    sb_putc(sb, '"');
    for (; *s; s++) {
        unsigned char c = (unsigned char)*s;
        switch (c) {
            case '"':  sb_puts(sb, "\\\""); break;
            case '\\': sb_puts(sb, "\\\\"); break;
            case '\b': sb_puts(sb, "\\b");  break;
            case '\f': sb_puts(sb, "\\f");  break;
            case '\n': sb_puts(sb, "\\n");  break;
            case '\r': sb_puts(sb, "\\r");  break;
            case '\t': sb_puts(sb, "\\t");  break;
            default:
                if (c < 0x20) {
                    char esc[7];
                    snprintf(esc, sizeof(esc), "\\u%04x", c);
                    sb_puts(sb, esc);
                } else {
                    sb_putc(sb, (char)c);
                }
        }
    }
    sb_putc(sb, '"');
}

static void sb_json_int(sb_t* sb, long v)
{
    char tmp[32];
    snprintf(tmp, sizeof(tmp), "%ld", v);
    sb_puts(sb, tmp);
}

static void sb_json_hex32(sb_t* sb, unsigned long v)
{
    char tmp[16];
    snprintf(tmp, sizeof(tmp), "\"0x%08lX\"", v & 0xFFFFFFFFUL);
    sb_puts(sb, tmp);
}

/* Append `"key":` (object member key). */
static void sb_key(sb_t* sb, const char* k)
{
    sb_json_str(sb, k);
    sb_putc(sb, ':');
}

/* ---- enum -> token ---- */
static const char* dir_str(bsdl_dir_t d)
{
    switch (d) {
        case BSDL_DIR_IN:      return "in";
        case BSDL_DIR_OUT:     return "out";
        case BSDL_DIR_INOUT:   return "inout";
        case BSDL_DIR_BUFFER:  return "buffer";
        case BSDL_DIR_LINKAGE: return "linkage";
        default:               return "unknown";
    }
}

static const char* tap_str(bsdl_tap_role_t t)
{
    switch (t) {
        case BSDL_TAP_TDI:  return "tdi";
        case BSDL_TAP_TDO:  return "tdo";
        case BSDL_TAP_TMS:  return "tms";
        case BSDL_TAP_TCK:  return "tck";
        case BSDL_TAP_TRST: return "trst";
        default:            return "none";
    }
}

static const char* cell_str(bsdl_cell_t c)
{
    switch (c) {
        case BSDL_CELL_BC1: return "BC_1";
        case BSDL_CELL_BC2: return "BC_2";
        case BSDL_CELL_BC3: return "BC_3";
        case BSDL_CELL_BC4: return "BC_4";
        case BSDL_CELL_BC5: return "BC_5";
        case BSDL_CELL_BC6: return "BC_6";
        case BSDL_CELL_BC7: return "BC_7";
        default:            return "unknown";
    }
}

static const char* bittype_str(bsdl_bittype_t b)
{
    switch (b) {
        case BSDL_BIT_INPUT:    return "input";
        case BSDL_BIT_OUTPUT:   return "output";
        case BSDL_BIT_TRISTATE: return "tristate";
        case BSDL_BIT_INOUT:    return "inout";
        case BSDL_BIT_CONTROL:  return "control";
        case BSDL_BIT_INTERNAL: return "internal";
        default:                return "unknown";
    }
}

static const char* state_str(bsdl_state_t s)
{
    switch (s) {
        case BSDL_STATE_UNDEF: return "X";
        case BSDL_STATE_HIGH:  return "1";
        case BSDL_STATE_LOW:   return "0";
        case BSDL_STATE_HIGHZ: return "Z";
        default:               return "unknown";
    }
}

char* bsdl_to_json(const bsdl_t* m)
{
    sb_t sb = { NULL, 0, 0, 0 };
    size_t i;

    if (!m)
        return NULL;

    sb_putc(&sb, '{');

    sb_key(&sb, "entity");             sb_json_str(&sb, m->entity);             sb_putc(&sb, ',');
    sb_key(&sb, "src_filename");       sb_json_str(&sb, m->src_filename);       sb_putc(&sb, ',');
    sb_key(&sb, "idcode");             sb_json_hex32(&sb, m->idcode);           sb_putc(&sb, ',');
    sb_key(&sb, "idcode_mask");        sb_json_hex32(&sb, m->idcode_mask);      sb_putc(&sb, ',');
    sb_key(&sb, "instruction_length"); sb_json_int(&sb, m->instruction_length); sb_putc(&sb, ',');

    /* pins */
    sb_key(&sb, "pins");
    sb_putc(&sb, '[');
    for (i = 0; i < m->pin_count; i++) {
        const bsdl_pin_t* p = &m->pins[i];
        if (i) sb_putc(&sb, ',');
        sb_putc(&sb, '{');
        sb_key(&sb, "name");         sb_json_str(&sb, p->name);          sb_putc(&sb, ',');
        sb_key(&sb, "dir");          sb_json_str(&sb, dir_str(p->dir));  sb_putc(&sb, ',');
        sb_key(&sb, "physical_pin"); sb_json_str(&sb, p->physical_pin);  sb_putc(&sb, ',');
        sb_key(&sb, "tap_role");     sb_json_str(&sb, tap_str(p->tap_role)); sb_putc(&sb, ',');
        sb_key(&sb, "in_bit");       sb_json_int(&sb, p->in_bit);        sb_putc(&sb, ',');
        sb_key(&sb, "out_bit");      sb_json_int(&sb, p->out_bit);       sb_putc(&sb, ',');
        sb_key(&sb, "ctrl_bit");     sb_json_int(&sb, p->ctrl_bit);
        sb_putc(&sb, '}');
    }
    sb_putc(&sb, ']');
    sb_putc(&sb, ',');

    /* boundary chain */
    sb_key(&sb, "chain");
    sb_putc(&sb, '[');
    for (i = 0; i < m->chain_count; i++) {
        const bsdl_cell_entry_t* c = &m->chain[i];
        if (i) sb_putc(&sb, ',');
        sb_putc(&sb, '{');
        sb_key(&sb, "index");          sb_json_int(&sb, c->index);                 sb_putc(&sb, ',');
        sb_key(&sb, "cell");           sb_json_str(&sb, cell_str(c->cell));        sb_putc(&sb, ',');
        sb_key(&sb, "port");           sb_json_str(&sb, c->port);                  sb_putc(&sb, ',');
        sb_key(&sb, "type");           sb_json_str(&sb, bittype_str(c->type));     sb_putc(&sb, ',');
        sb_key(&sb, "safe");           sb_json_str(&sb, state_str(c->safe));       sb_putc(&sb, ',');
        sb_key(&sb, "ctrl_index");     sb_json_int(&sb, c->ctrl_index);            sb_putc(&sb, ',');
        sb_key(&sb, "disable_state");  sb_json_str(&sb, state_str(c->disable_state));  sb_putc(&sb, ',');
        sb_key(&sb, "disable_result"); sb_json_str(&sb, state_str(c->disable_result));
        sb_putc(&sb, '}');
    }
    sb_putc(&sb, ']');
    sb_putc(&sb, ',');

    /* instructions */
    sb_key(&sb, "instructions");
    sb_putc(&sb, '[');
    for (i = 0; i < m->instruction_count; i++) {
        const bsdl_instr_t* in = &m->instructions[i];
        if (i) sb_putc(&sb, ',');
        sb_putc(&sb, '{');
        sb_key(&sb, "name");   sb_json_str(&sb, in->name);   sb_putc(&sb, ',');
        sb_key(&sb, "opcode"); sb_json_str(&sb, in->opcode);
        sb_putc(&sb, '}');
    }
    sb_putc(&sb, ']');

    sb_putc(&sb, '}');

    if (sb.oom) {
        free(sb.buf);
        return NULL;
    }
    sb.buf[sb.len] = '\0';
    return sb.buf;
}

void bsdl_string_free(char* s)
{
    free(s);
}