#include "parser.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <dirent.h>

static void str_trim(char *s) {
    char *e;
    while (isspace((unsigned char)*s)) s++;
    if (*s == 0) return;
    e = s + strlen(s) - 1;
    while (e > s && isspace((unsigned char)*e)) e--;
    *(e + 1) = '\0';
}

static int str_split(const char *line, char **key, char **val) {
    static char buf[MAX_LINE];
    strncpy(buf, line, sizeof(buf) - 1);
    buf[sizeof(buf) - 1] = '\0';
    char *eq = strchr(buf, ' ');
    if (!eq) { *key = buf; *val = ""; return 0; }
    *eq = '\0';
    *key = buf;
    *val = eq + 1;
    str_trim(*key);
    str_trim(*val);
    return 1;
}

static int str_to_int(const char *s) {
    if (strncmp(s, "0x", 2) == 0 || strncmp(s, "0X", 2) == 0)
        return (int)strtol(s, NULL, 16);
    return atoi(s);
}

static int str_to_bool(const char *s) {
    return strcmp(s, "true") == 0 || strcmp(s, "yes") == 0 || strcmp(s, "1") == 0;
}

static int parse_block(FILE *f, const char *block_type, const char *block_name, IsaDb *db) {
    char line[MAX_LINE];

    if (strcasecmp(block_type, "FORMAT") == 0) {
        if (db->num_formats >= MAX_FMTS) {
            fprintf(stderr, "Too many formats (max %d)\n", MAX_FMTS);
            return -1;
        }
        IsaFormat *fmt = &db->formats[db->num_formats];
        strncpy(fmt->name, block_name, MAX_NAME - 1);
        fmt->width = 32;
        fmt->num_fields = 0;

        while (fgets(line, sizeof(line), f)) {
            char *trimmed = line;
            while (isspace((unsigned char)*trimmed)) trimmed++;
            if (*trimmed == '#' || *trimmed == '\n') continue;
            if (strncmp(trimmed, "END", 3) == 0) break;

            char *key, *val;
            str_split(trimmed, &key, &val);

            if (strcasecmp(key, "WIDTH") == 0) {
                fmt->width = str_to_int(val);
            } else if (strcasecmp(key, "FIELD") == 0) {
                if (fmt->num_fields >= MAX_FIELDS) {
                    fprintf(stderr, "Too many fields in format %s\n", fmt->name);
                    continue;
                }
                char fname[64];
                int high, low;
                if (sscanf(val, "%63s %d:%d", fname, &high, &low) >= 3) {
                    strncpy(fmt->fields[fmt->num_fields].name, fname, MAX_LABEL - 1);
                    fmt->fields[fmt->num_fields].high = high;
                    fmt->fields[fmt->num_fields].low = low;
                    fmt->num_fields++;
                }
            }
        }
        db->num_formats++;
    } else if (strcasecmp(block_type, "REGISTER") == 0) {
        if (db->num_registers >= MAX_REGS) {
            fprintf(stderr, "Too many registers (max %d)\n", MAX_REGS);
            return -1;
        }
        IsaRegister *reg = &db->registers[db->num_registers];
        memset(reg, 0, sizeof(*reg));
        strncpy(reg->name, block_name, MAX_NAME - 1);
        reg->preserve = -1;

        while (fgets(line, sizeof(line), f)) {
            char *trimmed = line;
            while (isspace((unsigned char)*trimmed)) trimmed++;
            if (*trimmed == '#' || *trimmed == '\n') continue;
            if (strncmp(trimmed, "END", 3) == 0) break;

            char *key, *val;
            str_split(trimmed, &key, &val);

            if (strcasecmp(key, "ABBR") == 0)
                strncpy(reg->abbr, val, MAX_LABEL - 1);
            else if (strcasecmp(key, "DESC") == 0)
                strncpy(reg->desc, val, MAX_DESC - 1);
            else if (strcasecmp(key, "PRESERVE") == 0)
                reg->preserve = str_to_bool(val);
            else if (strcasecmp(key, "CALLER") == 0)
                reg->caller_saved = str_to_bool(val);
            else if (strcasecmp(key, "ARG") == 0)
                reg->arg_reg = str_to_bool(val);
            else if (strcasecmp(key, "INDEX") == 0)
                reg->index = str_to_int(val);
        }
        if (reg->preserve == -1) reg->preserve = 0;
        db->num_registers++;
    } else if (strcasecmp(block_type, "INSTRUCTION") == 0) {
        if (db->num_instructions >= MAX_INSTS) {
            fprintf(stderr, "Too many instructions (max %d)\n", MAX_INSTS);
            return -1;
        }
        IsaInstruction *inst = &db->instructions[db->num_instructions];
        memset(inst, 0, sizeof(*inst));
        strncpy(inst->name, block_name, MAX_NAME - 1);
        inst->funct3_valid = 0;
        inst->funct7_valid = 0;

        while (fgets(line, sizeof(line), f)) {
            char *trimmed = line;
            while (isspace((unsigned char)*trimmed)) trimmed++;
            if (*trimmed == '#' || *trimmed == '\n') continue;
            if (strncmp(trimmed, "END", 3) == 0) break;

            char *key, *val;
            str_split(trimmed, &key, &val);

            if (strcasecmp(key, "FORMAT") == 0)
                strncpy(inst->fmt_name, val, MAX_NAME - 1);
            else if (strcasecmp(key, "OPCODE") == 0)
                inst->opcode = (uint32_t)str_to_int(val);
            else if (strcasecmp(key, "FUNCT3") == 0) {
                inst->funct3 = (uint32_t)str_to_int(val);
                inst->funct3_valid = 1;
            } else if (strcasecmp(key, "FUNCT7") == 0) {
                inst->funct7 = (uint32_t)str_to_int(val);
                inst->funct7_valid = 1;
            } else if (strcasecmp(key, "OPERANDS") == 0)
                strncpy(inst->operands, val, MAX_OPERANDS - 1);
            else if (strcasecmp(key, "DESC") == 0)
                strncpy(inst->desc, val, MAX_DESC - 1);
            else if (strcasecmp(key, "NOTE") == 0)
                strncpy(inst->note, val, MAX_NOTE - 1);
            else if (strcasecmp(key, "CATEGORY") == 0)
                strncpy(inst->category, val, MAX_LABEL - 1);
            else if (strcasecmp(key, "IMM") == 0)
                inst->has_imm = str_to_bool(val);
        }
        db->num_instructions++;
    } else if (strcasecmp(block_type, "CSR") == 0) {
        if (db->num_csrs >= MAX_CSRS) {
            fprintf(stderr, "Too many CSRs (max %d)\n", MAX_CSRS);
            return -1;
        }
        IsaCsr *csr = &db->csrs[db->num_csrs];
        memset(csr, 0, sizeof(*csr));
        strncpy(csr->name, block_name, MAX_NAME - 1);

        while (fgets(line, sizeof(line), f)) {
            char *trimmed = line;
            while (isspace((unsigned char)*trimmed)) trimmed++;
            if (*trimmed == '#' || *trimmed == '\n') continue;
            if (strncmp(trimmed, "END", 3) == 0) break;

            char *key, *val;
            str_split(trimmed, &key, &val);

            if (strcasecmp(key, "NUMBER") == 0)
                csr->number = str_to_int(val);
            else if (strcasecmp(key, "DESC") == 0)
                strncpy(csr->desc, val, MAX_DESC - 1);
        }
        db->num_csrs++;
    } else if (strcasecmp(block_type, "ARCH") == 0) {
        while (fgets(line, sizeof(line), f)) {
            char *trimmed = line;
            while (isspace((unsigned char)*trimmed)) trimmed++;
            if (*trimmed == '#' || *trimmed == '\n') continue;
            if (strncmp(trimmed, "END", 3) == 0) break;

            char *key, *val;
            str_split(trimmed, &key, &val);

            if (strcasecmp(key, "NAME") == 0)
                strncpy(db->arch_name, val, MAX_NAME - 1);
            else if (strcasecmp(key, "VERSION") == 0)
                strncpy(db->arch_version, val, MAX_LABEL - 1);
            else if (strcasecmp(key, "DATE") == 0)
                strncpy(db->arch_date, val, MAX_LABEL - 1);
            else if (strcasecmp(key, "STATUS") == 0)
                strncpy(db->arch_status, val, MAX_LABEL - 1);
        }
    }

    return 0;
}

int isa_parse_file(const char *path, IsaDb *db) {
    FILE *f = fopen(path, "r");
    if (!f) {
        fprintf(stderr, "Error: cannot open %s\n", path);
        return -1;
    }

    char line[MAX_LINE];
    int line_num = 0;

    while (fgets(line, sizeof(line), f)) {
        line_num++;
        char *trimmed = line;
        while (isspace((unsigned char)*trimmed)) trimmed++;
        if (*trimmed == '#' || *trimmed == '\n' || *trimmed == '\r') continue;

        char type[MAX_LABEL], name[MAX_NAME];
        if (sscanf(trimmed, "%31s %63s", type, name) >= 2) {
            if (parse_block(f, type, name, db) != 0) {
                fprintf(stderr, "Error parsing %s in %s line %d\n", type, path, line_num);
                fclose(f);
                return -1;
            }
        }
    }

    fclose(f);
    return 0;
}

int isa_parse_dir(const char *dir, IsaDb *db) {
    DIR *d = opendir(dir);
    if (!d) {
        fprintf(stderr, "Error: cannot open directory %s\n", dir);
        return -1;
    }

    struct dirent *entry;
    while ((entry = readdir(d)) != NULL) {
        if (entry->d_type != DT_REG) continue;
        const char *ext = strrchr(entry->d_name, '.');
        if (!ext || strcasecmp(ext, ".isa") != 0) continue;

        char path[MAX_PATH];
        snprintf(path, sizeof(path), "%s/%s", dir, entry->d_name);
        printf("  Parsing: %s\n", path);
        isa_parse_file(path, db);
    }

    closedir(d);
    return 0;
}