from pybtc import int_to_c_int, c_int_to_int, c_int_len
import asyncio
from collections import OrderedDict
from pybtc  import MRU

class UTXO():
    def __init__(self, db_pool, loop, log, cache_size):
        self.cached = MRU()
        self.missed = set()
        self.deleted = set()
        self.pending_deleted = set()
        self.checkpoints = list()
        self.log = log
        self.loaded = MRU()
        self.pending_saved = OrderedDict()
        self.maturity = 100
        self.size_limit = cache_size
        self._db_pool = db_pool
        self.loop = loop
        self.clear_tail = False
        self.last_saved_block = 0
        self.last_cached_block = 0
        self.save_process = False
        self.load_utxo_future = asyncio.Future()
        self.load_utxo_future.set_result(True)
        self._requests = 0
        self._failed_requests = 0
        self._hit = 0
        self.saved_utxo = 0
        self.deleted_utxo = 0
        self.deleted_last_block = 0
        self.deleted_utxo_saved = 0
        self.loaded_utxo = 0
        self.destroyed_utxo = 0
        self.destroyed_utxo_block = 0
        self.outs_total = 0

    def set(self, outpoint, pointer, amount, address):
        # self.cached.put({outpoint: (pointer, amount, address)})
        self.cached[outpoint] = (pointer, amount, address)

    def remove(self, outpoint):
        del self.cached[outpoint]


    async def save_utxo(self):
        # save to db tail from cache
        if  self.save_process or not self.cached: return
        if  not self.checkpoints: return

        self.save_process = True
        try:
            # self.log.critical("cached " + str(len(self.cached)) )
            i = self.cached.peek_last_item()
            self.checkpoints = sorted(self.checkpoints)
            checkpoint = self.checkpoints.pop(0)
            lb = 0
            block_changed = False
            checkpoint_found = False
            utxo = set()
            while self.cached:
                i = self.cached.pop()
                if lb != i[1][0] >> 42:
                    block_changed = True
                    lb = i[1][0] >> 42
                if lb - 1 == checkpoint:
                    if len(self.cached) > int(self.size_limit * 0.9):
                        if self.checkpoints:
                            checkpoint = self.checkpoints.pop(0)
                    else:
                        checkpoint_found = True
                while self.checkpoints and checkpoint < lb - 1:
                    checkpoint = self.checkpoints.pop(0)



                if len(self.cached) <= self.size_limit:
                    if block_changed and checkpoint_found:
                        break
                utxo.add((i[0],b"".join((int_to_c_int(i[1][0]),
                                         int_to_c_int(i[1][1]),
                                         i[1][2]))))
                self.pending_saved[i[0]] = i[1]
            if block_changed:
                self.cached.append({i[0]: i[1]})
                lb -= 1
            if not checkpoint_found:
                for i in reversed(self.pending_saved):
                    self.cached.append({i: self.pending_saved[i]})
                self.log.critical("checkpoint not found " +str(lb) +" > "+ str(self.checkpoints))
                await asyncio.sleep(5)
                return


            async with self._db_pool.acquire() as conn:
                async with conn.transaction():
                    if self.pending_deleted:
                        await conn.execute("DELETE FROM connector_utxo WHERE "
                                           "outpoint = ANY($1);", self.pending_deleted)
                    if utxo:
                        await conn.copy_records_to_table('connector_utxo',
                                                         columns=["outpoint", "data"], records=utxo)
                    await conn.execute("UPDATE connector_utxo_state SET value = $1 "
                                       "WHERE name = 'last_block';", lb)
                    await conn.execute("UPDATE connector_utxo_state SET value = $1 "
                                       "WHERE name = 'last_cached_block';", self.deleted_last_block)
            self.saved_utxo += len(utxo)
            self.deleted_utxo += len(self.pending_deleted)
            self.pending_deleted = set()


            self.last_saved_block = lb
        except:
            import traceback
            self.log.critical("implement rollback  ")
            self.log.critical(str(traceback.format_exc()))
        finally:
            self.pending_saved = OrderedDict()
            self.save_process = False

    def get(self, key):
        self._requests += 1
        try:
            i = self.cached.delete(key)
            self._hit += 1
            return i
        except:
            try:
                i = self.pending_saved[key]
                self._hit += 1
                return i
            except:
                self._failed_requests += 1
                self.missed.add(key)
                return None

    def get_loaded(self, key):
        try:
            self.deleted.add(key)
            return self.loaded.delete(key)
        except:
            return None

    async def load_utxo(self):
        while True:
            if not self.load_utxo_future.done():
                await self.load_utxo_future
                continue
            break
        try:
            self.load_utxo_future = asyncio.Future()
            l = set(self.missed)
            async with self._db_pool.acquire() as conn:
                rows = await conn.fetch("SELECT outpoint, connector_utxo.data "
                                        "FROM connector_utxo "
                                        "WHERE outpoint = ANY($1);", l)
            for i in l:
                try:
                    self.missed.remove(i)
                except:
                    pass
            for row in rows:
                d = row["data"]
                pointer = c_int_to_int(d)
                f = c_int_len(pointer)
                amount = c_int_to_int(d[f:])
                f += c_int_len(amount)
                address = d[f:]
                self.loaded[row["outpoint"]] = (pointer, amount, address)
                self.loaded_utxo += 1
        finally:
            self.load_utxo_future.set_result(True)


    def len(self):
        return len(self.cached)

    def hit_rate(self):
        if self._requests:
            return self._hit / self._requests
        else:
            return 0