/**
 * This file is part of the Fun programming language.
 * https://fun-lang.xyz/
 *
 * Copyright 2025 Johannes Findeisen <you@hanez.org>
 * Licensed under the terms of the Apache-2.0 license.
 * https://opensource.org/license/apache-2-0
 */

#include "value.h"
#include <stdlib.h>
#include <string.h>
#include <stdio.h>

/* Compile helper implementations into this TU to avoid build system changes */
#include "str_utils.c"
#include "array_utils.c"

typedef struct Array {
    int refcount;
    int count;
    Value *items; /* owns items; each item owned by array */
} Array;

typedef struct Map {
    int refcount;
    int count;
    int cap;
    char **keys;   /* each key owned here */
    Value *vals;   /* each value owned here */
} Map;

Value make_int(int64_t v) {
    Value val;
    val.type = VAL_INT;
    val.i = v;
    return val;
}

Value make_float(double v) {
    Value val;
    val.type = VAL_FLOAT;
    val.d = v;
    return val;
}

Value make_bool(int v) {
    Value val;
    val.type = VAL_BOOL;
    val.i = v ? 1 : 0;
    return val;
}

Value make_string(const char *s) {
    Value val;
    val.type = VAL_STRING;
    if (s) val.s = strdup(s);
    else val.s = strdup("");
    return val;
}

Value make_function(struct Bytecode *fn) {
    Value val;
    val.type = VAL_FUNCTION;
    val.fn = fn;
    return val;
}

Value make_nil(void) {
    Value v;
    v.type = VAL_NIL;
    return v;
}


Value make_array_from_values(const Value *vals, int count) {
    if (count < 0) count = 0;
    Array *arr = (Array*)malloc(sizeof(Array));
    if (!arr) {
        Value nil = make_nil();
        return nil;
    }
    arr->refcount = 1;
    arr->count = count;
    if (count > 0) {
        arr->items = (Value*)malloc(sizeof(Value) * count);
        if (!arr->items) {
            free(arr);
            Value nil = make_nil();
            return nil;
        }
        for (int i = 0; i < count; ++i) {
            arr->items[i] = copy_value(&vals[i]);
        }
    } else {
        arr->items = NULL;
    }
    Value v;
    v.type = VAL_ARRAY;
    v.arr = (struct Array*)arr;
    return v;
}

int array_length(const Value *v) {
    if (!v || v->type != VAL_ARRAY || !v->arr) return -1;
    const Array *a = (const Array*)v->arr;
    return a->count;
}

int array_get_copy(const Value *v, int index, Value *out) {
    if (!v || v->type != VAL_ARRAY || !v->arr) return 0;
    const Array *a = (const Array*)v->arr;
    if (index < 0 || index >= a->count) return 0;
    if (out) *out = copy_value(&a->items[index]);
    return 1;
}

int array_set(Value *v, int index, Value newElem) {
    if (!v || v->type != VAL_ARRAY || !v->arr) return 0;
    Array *a = (Array*)v->arr;
    if (index < 0 || index >= a->count) return 0;
    free_value(a->items[index]);
    a->items[index] = newElem; /* take ownership */
    return 1;
}

static int ensure_array_capacity(Array *a, int newCount) {
    if (newCount <= a->count) return 1;
    /* grow to at least newCount; double strategy */
    int curr = a->count;
    int cap = curr;
    if (cap < 4) cap = 4;
    while (cap < newCount) cap *= 2;
    Value *newItems = (Value*)realloc(a->items, sizeof(Value) * cap);
    if (!newItems) return 0;
    /* if growing beyond current count, initialize new slots to nil */
    if (cap > a->count) {
        for (int i = a->count; i < cap; ++i) {
            newItems[i] = make_nil();
        }
    }
    a->items = newItems;
    return 1;
}

int array_push(Value *v, Value newElem) {
    if (!v || v->type != VAL_ARRAY || !v->arr) return -1;
    Array *a = (Array*)v->arr;
    /* ensure capacity for count+1 by reallocating items array to at least count+1 elements */
    Value *newItems = (Value*)realloc(a->items, sizeof(Value) * (a->count + 1));
    if (!newItems) { free_value(newElem); return -1; }
    a->items = newItems;
    a->items[a->count] = newElem; /* take ownership */
    a->count += 1;
    return a->count;
}

int array_pop(Value *v, Value *out) {
    if (!v || v->type != VAL_ARRAY || !v->arr) return 0;
    Array *a = (Array*)v->arr;
    if (a->count <= 0) return 0;
    int idx = a->count - 1;
    if (out) *out = a->items[idx]; /* transfer ownership */
    else free_value(a->items[idx]);
    a->count -= 1;
    return 1;
}

int array_insert(Value *v, int index, Value newElem) {
    if (!v || v->type != VAL_ARRAY || !v->arr) return -1;
    Array *a = (Array*)v->arr;
    if (index < 0) index = 0;
    if (index > a->count) index = a->count;
    Value *newItems = (Value*)realloc(a->items, sizeof(Value) * (a->count + 1));
    if (!newItems) { free_value(newElem); return -1; }
    a->items = newItems;
    /* shift right */
    for (int i = a->count; i > index; --i) {
        a->items[i] = a->items[i - 1];
    }
    a->items[index] = newElem; /* take ownership */
    a->count += 1;
    return a->count;
}

int array_remove(Value *v, int index, Value *out) {
    if (!v || v->type != VAL_ARRAY || !v->arr) return 0;
    Array *a = (Array*)v->arr;
    if (index < 0 || index >= a->count) return 0;
    if (out) *out = a->items[index]; /* transfer ownership */
    else free_value(a->items[index]);
    /* shift left */
    for (int i = index; i < a->count - 1; ++i) {
        a->items[i] = a->items[i + 1];
    }
    a->count -= 1;
    return 1;
}

Value array_slice(const Value *v, int start, int end) {
    if (!v || v->type != VAL_ARRAY || !v->arr) return make_nil();
    const Array *a = (const Array*)v->arr;
    int n = a->count;
    if (start < 0) start = 0;
    if (end < 0 || end > n) end = n;
    if (start > end) start = end;
    int m = end - start;
    if (m <= 0) {
        return make_array_from_values(NULL, 0);
    }
    return make_array_from_values(a->items + start, m);
}

Value array_concat(const Value *av, const Value *bv) {
    if (!av || !bv || av->type != VAL_ARRAY || bv->type != VAL_ARRAY) return make_nil();
    const Array *a = (const Array*)av->arr;
    const Array *b = (const Array*)bv->arr;
    int na = a ? a->count : 0;
    int nb = b ? b->count : 0;
    int total = na + nb;
    if (total <= 0) return make_array_from_values(NULL, 0);
    Value *tmp = (Value*)malloc(sizeof(Value) * total);
    if (!tmp) return make_nil();
    for (int i = 0; i < na; ++i) tmp[i] = a->items[i];
    for (int j = 0; j < nb; ++j) tmp[na + j] = b->items[j];
    Value out = make_array_from_values(tmp, total);
    /* free temporaries we copied from (deep copy in make_array_from_values) */
    free(tmp);
    return out;
}

Value copy_value(const Value *v) {
    Value out;
    out.type = v->type;
    switch (v->type) {
        case VAL_INT:
            out.i = v->i;
            break;
        case VAL_FLOAT:
            out.d = v->d;
            break;
        case VAL_BOOL:
            out.i = v->i ? 1 : 0;
            break;
        case VAL_STRING:
            out.s = v->s ? strdup(v->s) : strdup("");
            break;
        case VAL_FUNCTION:
            out.fn = v->fn; /* shallow copy pointer */
            break;
        case VAL_ARRAY: {
            Array *a = (Array*)v->arr;
            out.arr = (struct Array*)a;
            if (a) a->refcount++;
            break;
        }
        case VAL_MAP: {
            Map *m = (Map*)v->map;
            out.map = (struct Map*)m;
            if (m) m->refcount++;
            break;
        }
        case VAL_NIL:
        default:
            break;
    }
    return out;
}

/* deep copy including arrays (recursively copies items) */
Value deep_copy_value(const Value *v) {
    switch (v->type) {
        case VAL_INT:
            return make_int(v->i);
        case VAL_FLOAT:
            return make_float(v->d);
        case VAL_BOOL:
            return make_bool(v->i);
        case VAL_STRING:
            return make_string(v->s ? v->s : "");
        case VAL_FUNCTION:
            return make_function(v->fn); /* shallow pointer for function bytecode */
        case VAL_ARRAY: {
            const Array *a = (const Array*)v->arr;
            if (!a || a->count <= 0) {
                return make_array_from_values(NULL, 0);
            }
            /* copy items deeply */
            Value *tmp = (Value*)malloc(sizeof(Value) * a->count);
            if (!tmp) return make_nil();
            for (int i = 0; i < a->count; ++i) {
                tmp[i] = deep_copy_value(&a->items[i]);
            }
            Value out = make_array_from_values(tmp, a->count);
            for (int i = 0; i < a->count; ++i) {
                free_value(tmp[i]);
            }
            free(tmp);
            return out;
        }
        case VAL_MAP: {
            const Map *m = (const Map*)v->map;
            if (!m || m->count <= 0) return make_map_empty();
            Value out = make_map_empty();
            for (int i = 0; i < m->count; ++i) {
                Value dv = deep_copy_value(&m->vals[i]);
                map_set(&out, m->keys[i], dv);
            }
            return out;
        }
        case VAL_NIL:
        default:
            return make_nil();
    }
}

void free_value(Value v) {
    if (v.type == VAL_STRING && v.s) {
        free(v.s);
    } else if (v.type == VAL_ARRAY && v.arr) {
        Array *a = (Array*)v.arr;
        if (--a->refcount == 0) {
            for (int i = 0; i < a->count; ++i) {
                free_value(a->items[i]);
            }
            free(a->items);
            free(a);
        }
    } else if (v.type == VAL_MAP && v.map) {
        Map *m = (Map*)v.map;
        if (--m->refcount == 0) {
            for (int i = 0; i < m->count; ++i) {
                if (m->keys[i]) free(m->keys[i]);
                free_value(m->vals[i]);
            }
            free(m->keys);
            free(m->vals);
            free(m);
        }
    }
    /* VAL_FUNCTION: we *do not* free the Bytecode here (caller frees it) */
}

void print_value(const Value *v) {
    switch (v->type) {
        case VAL_INT:
            printf("%" PRId64, v->i);
            break;
        case VAL_FLOAT:
            printf("%.17g", v->d);
            break;
        case VAL_STRING:
            printf("%s", v->s ? v->s : "");
            break;
        case VAL_BOOL:
            printf("%s", v->i ? "true" : "false");
            break;
        case VAL_FUNCTION:
            printf("<function@%p>", (void*)v->fn);
            break;
        case VAL_ARRAY: {
            const Array *a = (const Array*)v->arr;
            printf("[");
            if (a) {
                for (int i = 0; i < a->count; ++i) {
                    if (i > 0) printf(", ");
                    print_value(&a->items[i]);
                }
            }
            printf("]");
            break;
        }
        case VAL_MAP: {
            const Map *m = (const Map*)v->map;
            printf("{");
            if (m) {
                for (int i = 0; i < m->count; ++i) {
                    if (i > 0) printf(", ");
                    printf("\"%s\": ", m->keys[i] ? m->keys[i] : "");
                    print_value(&m->vals[i]);
                }
            }
            printf("}");
            break;
        }
        case VAL_NIL:
        default:
            printf("nil");
            break;
    }
}

int value_is_truthy(const Value *v) {
    switch (v->type) {
        case VAL_INT:
            return v->i != 0;
        case VAL_FLOAT:
            return v->d != 0.0;
        case VAL_BOOL:
            return v->i != 0;
        case VAL_STRING:
            return v->s && v->s[0] != '\0';
        case VAL_FUNCTION:
            return 1;
        case VAL_ARRAY: {
            const Array *a = (const Array*)v->arr;
            return a && a->count > 0;
        }
        case VAL_NIL:
        default:
            return 0;
    }
}

/* allocate a printable C string for the value; caller must free */
char *value_to_string_alloc(const Value *v) {
    if (!v) return strdup("nil");
    char buf[128];
    switch (v->type) {
        case VAL_INT: {
            char tmp[64];
            snprintf(tmp, sizeof(tmp), "%" PRId64, v->i);
            return strdup(tmp);
        }
        case VAL_FLOAT: {
            char tmp[64];
            snprintf(tmp, sizeof(tmp), "%.17g", v->d);
            return strdup(tmp);
        }
        case VAL_STRING:
            return strdup(v->s ? v->s : "");
        case VAL_BOOL:
            return strdup(v->i ? "true" : "false");
        case VAL_FUNCTION: {
            snprintf(buf, sizeof(buf), "<function@%p>", (void*)v->fn);
            return strdup(buf);
        }
        case VAL_ARRAY: {
            int n = array_length(v);
            if (n < 0) n = 0;
            snprintf(buf, sizeof(buf), "[array n=%d]", n);
            return strdup(buf);
        }
        case VAL_MAP: {
            int n = 0;
            if (v->type == VAL_MAP && v->map) {
                const Map *m = (const Map*)v->map;
                n = m ? m->count : 0;
            }
            snprintf(buf, sizeof(buf), "{map n=%d}", n);
            return strdup(buf);
        }
        case VAL_NIL:
        default:
            return strdup("nil");
    }
}

int value_equals(const Value *a, const Value *b) {
    // Numeric cross-type equality: int vs float compares numerically
    if ((a->type == VAL_INT || a->type == VAL_FLOAT) && (b->type == VAL_INT || b->type == VAL_FLOAT)) {
        double da = (a->type == VAL_INT) ? (double)a->i : a->d;
        double db = (b->type == VAL_INT) ? (double)b->i : b->d;
        return da == db;
    }
    if (a->type != b->type) return 0;
    switch (a->type) {
        case VAL_INT: return a->i == b->i;
        case VAL_BOOL: return (a->i != 0) == (b->i != 0);
        case VAL_STRING: {
            const char *sa = a->s ? a->s : "";
            const char *sb = b->s ? b->s : "";
            return strcmp(sa, sb) == 0;
        }
        default: return 0;
    }
}