// Copyright (c) 2016 Paul Sokolovsky
// SPDX-FileCopyrightText: 2014 MicroPython & CircuitPython contributors (https://github.com/adafruit/circuitpython/graphs/contributors)
//
// SPDX-License-Identifier: MIT

#include <stdio.h>
#include <string.h>
#include <errno.h> // for declaration of global errno variable
#include <fcntl.h>

#include "py/runtime.h"
#include "py/stream.h"

#if MICROPY_PY_BTREE

#include <db.h>
#include <../../btree/btree.h>

typedef struct _mp_obj_btree_t {
    mp_obj_base_t base;
    DB *db;
    mp_obj_t start_key;
    mp_obj_t end_key;
    #define FLAG_END_KEY_INCL 1
    #define FLAG_DESC 2
    #define FLAG_ITER_TYPE_MASK 0xc0
    #define FLAG_ITER_KEYS   0x40
    #define FLAG_ITER_VALUES 0x80
    #define FLAG_ITER_ITEMS  0xc0
    byte flags;
    byte next_flags;
} mp_obj_btree_t;

STATIC const mp_obj_type_t btree_type;

#define CHECK_ERROR(res) \
    if (res == RET_ERROR) { \
        mp_raise_OSError(errno); \
    }

void __dbpanic(DB *db) {
    printf("__dbpanic(%p)\n", db);
}

STATIC mp_obj_btree_t *btree_new(DB *db) {
    mp_obj_btree_t *o = m_new_obj(mp_obj_btree_t);
    o->base.type = &btree_type;
    o->db = db;
    o->start_key = mp_const_none;
    o->end_key = mp_const_none;
    o->next_flags = 0;
    return o;
}

STATIC void btree_print(const mp_print_t *print, mp_obj_t self_in, mp_print_kind_t kind) {
    (void)kind;
    mp_obj_btree_t *self = MP_OBJ_TO_PTR(self_in);
    mp_printf(print, "<btree %p>", self->db);
}

STATIC mp_obj_t btree_flush(mp_obj_t self_in) {
    mp_obj_btree_t *self = MP_OBJ_TO_PTR(self_in);
    return MP_OBJ_NEW_SMALL_INT(__bt_sync(self->db, 0));
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(btree_flush_obj, btree_flush);

STATIC mp_obj_t btree_close(mp_obj_t self_in) {
    mp_obj_btree_t *self = MP_OBJ_TO_PTR(self_in);
    return MP_OBJ_NEW_SMALL_INT(__bt_close(self->db));
}
STATIC MP_DEFINE_CONST_FUN_OBJ_1(btree_close_obj, btree_close);

STATIC mp_obj_t btree_put(size_t n_args, const mp_obj_t *args) {
    (void)n_args;
    mp_obj_btree_t *self = MP_OBJ_TO_PTR(args[0]);
    DBT key, val;
    key.data = (void *)mp_obj_str_get_data(args[1], &key.size);
    val.data = (void *)mp_obj_str_get_data(args[2], &val.size);
    return MP_OBJ_NEW_SMALL_INT(__bt_put(self->db, &key, &val, 0));
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(btree_put_obj, 3, 4, btree_put);

STATIC mp_obj_t btree_get(size_t n_args, const mp_obj_t *args) {
    mp_obj_btree_t *self = MP_OBJ_TO_PTR(args[0]);
    DBT key, val;
    key.data = (void *)mp_obj_str_get_data(args[1], &key.size);
    int res = __bt_get(self->db, &key, &val, 0);
    if (res == RET_SPECIAL) {
        if (n_args > 2) {
            return args[2];
        } else {
            return mp_const_none;
        }
    }
    CHECK_ERROR(res);
    return mp_obj_new_bytes(val.data, val.size);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(btree_get_obj, 2, 3, btree_get);

STATIC mp_obj_t btree_seq(size_t n_args, const mp_obj_t *args) {
    mp_obj_btree_t *self = MP_OBJ_TO_PTR(args[0]);
    int flags = MP_OBJ_SMALL_INT_VALUE(args[1]);
    DBT key, val;
    if (n_args > 2) {
        key.data = (void *)mp_obj_str_get_data(args[2], &key.size);
    }

    int res = __bt_seq(self->db, &key, &val, flags);
    CHECK_ERROR(res);
    if (res == RET_SPECIAL) {
        return mp_const_none;
    }

    mp_obj_t pair_o = mp_obj_new_tuple(2, NULL);
    mp_obj_tuple_t *pair = MP_OBJ_TO_PTR(pair_o);
    pair->items[0] = mp_obj_new_bytes(key.data, key.size);
    pair->items[1] = mp_obj_new_bytes(val.data, val.size);
    return pair_o;
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(btree_seq_obj, 2, 4, btree_seq);

STATIC mp_obj_t btree_init_iter(size_t n_args, const mp_obj_t *args, byte type) {
    mp_obj_btree_t *self = MP_OBJ_TO_PTR(args[0]);
    self->next_flags = type;
    self->start_key = mp_const_none;
    self->end_key = mp_const_none;
    if (n_args > 1) {
        self->start_key = args[1];
        if (n_args > 2) {
            self->end_key = args[2];
            if (n_args > 3) {
                self->next_flags = type | MP_OBJ_SMALL_INT_VALUE(args[3]);
            }
        }
    }
    return args[0];
}

STATIC mp_obj_t btree_keys(size_t n_args, const mp_obj_t *args) {
    return btree_init_iter(n_args, args, FLAG_ITER_KEYS);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(btree_keys_obj, 1, 4, btree_keys);

STATIC mp_obj_t btree_values(size_t n_args, const mp_obj_t *args) {
    return btree_init_iter(n_args, args, FLAG_ITER_VALUES);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(btree_values_obj, 1, 4, btree_values);

STATIC mp_obj_t btree_items(size_t n_args, const mp_obj_t *args) {
    return btree_init_iter(n_args, args, FLAG_ITER_ITEMS);
}
STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(btree_items_obj, 1, 4, btree_items);

STATIC mp_obj_t btree_getiter(mp_obj_t self_in, mp_obj_iter_buf_t *iter_buf) {
    (void)iter_buf;
    mp_obj_btree_t *self = MP_OBJ_TO_PTR(self_in);
    if (self->next_flags != 0) {
        // If we're called immediately after keys(), values(), or items(),
        // use their setup for iteration.
        self->flags = self->next_flags;
        self->next_flags = 0;
    } else {
        // Otherwise, iterate over all keys.
        self->flags = FLAG_ITER_KEYS;
        self->start_key = mp_const_none;
        self->end_key = mp_const_none;
    }

    return self_in;
}

STATIC mp_obj_t btree_iternext(mp_obj_t self_in) {
    mp_obj_btree_t *self = MP_OBJ_TO_PTR(self_in);
    DBT key, val;
    int res;
    bool desc = self->flags & FLAG_DESC;
    if (self->start_key != MP_OBJ_NULL) {
        int flags = R_FIRST;
        if (self->start_key != mp_const_none) {
            key.data = (void *)mp_obj_str_get_data(self->start_key, &key.size);
            flags = R_CURSOR;
        } else if (desc) {
            flags = R_LAST;
        }
        res = __bt_seq(self->db, &key, &val, flags);
        self->start_key = MP_OBJ_NULL;
    } else {
        res = __bt_seq(self->db, &key, &val, desc ? R_PREV : R_NEXT);
    }

    if (res == RET_SPECIAL) {
        return MP_OBJ_STOP_ITERATION;
    }
    CHECK_ERROR(res);

    if (self->end_key != mp_const_none) {
        DBT end_key;
        end_key.data = (void *)mp_obj_str_get_data(self->end_key, &end_key.size);
        BTREE *t = self->db->internal;
        int cmp = t->bt_cmp(&key, &end_key);
        if (desc) {
            cmp = -cmp;
        }
        if (self->flags & FLAG_END_KEY_INCL) {
            cmp--;
        }
        if (cmp >= 0) {
            self->end_key = MP_OBJ_NULL;
            return MP_OBJ_STOP_ITERATION;
        }
    }

    switch (self->flags & FLAG_ITER_TYPE_MASK) {
        case FLAG_ITER_KEYS:
            return mp_obj_new_bytes(key.data, key.size);
        case FLAG_ITER_VALUES:
            return mp_obj_new_bytes(val.data, val.size);
        default: {
            mp_obj_t pair_o = mp_obj_new_tuple(2, NULL);
            mp_obj_tuple_t *pair = MP_OBJ_TO_PTR(pair_o);
            pair->items[0] = mp_obj_new_bytes(key.data, key.size);
            pair->items[1] = mp_obj_new_bytes(val.data, val.size);
            return pair_o;
        }
    }
}

STATIC mp_obj_t btree_subscr(mp_obj_t self_in, mp_obj_t index, mp_obj_t value) {
    mp_obj_btree_t *self = mp_instance_cast_to_native_base(self_in, &btree_type);
    if (value == MP_OBJ_NULL) {
        // delete
        DBT key;
        key.data = (void *)mp_obj_str_get_data(index, &key.size);
        int res = __bt_delete(self->db, &key, 0);
        if (res == RET_SPECIAL) {
            nlr_raise(mp_obj_new_exception(&mp_type_KeyError));
        }
        CHECK_ERROR(res);
        return mp_const_none;
    } else if (value == MP_OBJ_SENTINEL) {
        // load
        DBT key, val;
        key.data = (void *)mp_obj_str_get_data(index, &key.size);
        int res = __bt_get(self->db, &key, &val, 0);
        if (res == RET_SPECIAL) {
            nlr_raise(mp_obj_new_exception(&mp_type_KeyError));
        }
        CHECK_ERROR(res);
        return mp_obj_new_bytes(val.data, val.size);
    } else {
        // store
        DBT key, val;
        key.data = (void *)mp_obj_str_get_data(index, &key.size);
        val.data = (void *)mp_obj_str_get_data(value, &val.size);
        int res = __bt_put(self->db, &key, &val, 0);
        CHECK_ERROR(res);
        return mp_const_none;
    }
}

STATIC mp_obj_t btree_binary_op(mp_binary_op_t op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
    mp_obj_btree_t *self = MP_OBJ_TO_PTR(lhs_in);
    switch (op) {
        case MP_BINARY_OP_CONTAINS: {
            DBT key, val;
            key.data = (void *)mp_obj_str_get_data(rhs_in, &key.size);
            int res = __bt_get(self->db, &key, &val, 0);
            CHECK_ERROR(res);
            return mp_obj_new_bool(res != RET_SPECIAL);
        }
        default:
            // op not supported
            return MP_OBJ_NULL;
    }
}

STATIC const mp_rom_map_elem_t btree_locals_dict_table[] = {
    { MP_ROM_QSTR(MP_QSTR_close), MP_ROM_PTR(&btree_close_obj) },
    { MP_ROM_QSTR(MP_QSTR_flush), MP_ROM_PTR(&btree_flush_obj) },
    { MP_ROM_QSTR(MP_QSTR_get), MP_ROM_PTR(&btree_get_obj) },
    { MP_ROM_QSTR(MP_QSTR_put), MP_ROM_PTR(&btree_put_obj) },
    { MP_ROM_QSTR(MP_QSTR_seq), MP_ROM_PTR(&btree_seq_obj) },
    { MP_ROM_QSTR(MP_QSTR_keys), MP_ROM_PTR(&btree_keys_obj) },
    { MP_ROM_QSTR(MP_QSTR_values), MP_ROM_PTR(&btree_values_obj) },
    { MP_ROM_QSTR(MP_QSTR_items), MP_ROM_PTR(&btree_items_obj) },
};

STATIC MP_DEFINE_CONST_DICT(btree_locals_dict, btree_locals_dict_table);

STATIC const mp_obj_type_t btree_type = {
    { &mp_type_type },
    // Save on qstr's, reuse same as for module
    .name = MP_QSTR_btree,
    .print = btree_print,
    .getiter = btree_getiter,
    .iternext = btree_iternext,
    .binary_op = btree_binary_op,
    .subscr = btree_subscr,
    .locals_dict = (void *)&btree_locals_dict,
};

STATIC FILEVTABLE btree_stream_fvtable = {
    mp_stream_posix_read,
    mp_stream_posix_write,
    mp_stream_posix_lseek,
    mp_stream_posix_fsync
};

STATIC mp_obj_t mod_btree_open(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
    static const mp_arg_t allowed_args[] = {
        { MP_QSTR_flags, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
        { MP_QSTR_cachesize, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
        { MP_QSTR_pagesize, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
        { MP_QSTR_minkeypage, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
    };

    // Make sure we got a stream object
    mp_get_stream_raise(pos_args[0], MP_STREAM_OP_READ | MP_STREAM_OP_WRITE | MP_STREAM_OP_IOCTL);

    struct {
        mp_arg_val_t flags;
        mp_arg_val_t cachesize;
        mp_arg_val_t pagesize;
        mp_arg_val_t minkeypage;
    } args;
    mp_arg_parse_all(n_args - 1, pos_args + 1, kw_args,
        MP_ARRAY_SIZE(allowed_args), allowed_args, (mp_arg_val_t *)&args);
    BTREEINFO openinfo = {0};
    openinfo.flags = args.flags.u_int;
    openinfo.cachesize = args.cachesize.u_int;
    openinfo.psize = args.pagesize.u_int;
    openinfo.minkeypage = args.minkeypage.u_int;

    DB *db = __bt_open(pos_args[0], &btree_stream_fvtable, &openinfo, /*dflags*/ 0);
    if (db == NULL) {
        mp_raise_OSError(errno);
    }
    return MP_OBJ_FROM_PTR(btree_new(db));
}
STATIC MP_DEFINE_CONST_FUN_OBJ_KW(mod_btree_open_obj, 1, mod_btree_open);

STATIC const mp_rom_map_elem_t mp_module_btree_globals_table[] = {
    { MP_ROM_QSTR(MP_QSTR___name__), MP_ROM_QSTR(MP_QSTR_btree) },
    { MP_ROM_QSTR(MP_QSTR_open), MP_ROM_PTR(&mod_btree_open_obj) },
    { MP_ROM_QSTR(MP_QSTR_INCL), MP_ROM_INT(FLAG_END_KEY_INCL) },
    { MP_ROM_QSTR(MP_QSTR_DESC), MP_ROM_INT(FLAG_DESC) },
};

STATIC MP_DEFINE_CONST_DICT(mp_module_btree_globals, mp_module_btree_globals_table);

const mp_obj_module_t mp_module_btree = {
    .base = { &mp_type_module },
    .globals = (mp_obj_dict_t *)&mp_module_btree_globals,
};

#endif // MICROPY_PY_BTREE