/* Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#define C_LUCY_LEXICONWRITER
#include "Lucy/Util/ToolSet.h"

#include "Lucy/Index/LexiconWriter.h"
#include "Lucy/Plan/FieldType.h"
#include "Lucy/Plan/Schema.h"
#include "Lucy/Index/PolyReader.h"
#include "Lucy/Index/Posting/MatchPosting.h"
#include "Lucy/Index/Segment.h"
#include "Lucy/Index/SegReader.h"
#include "Lucy/Index/Snapshot.h"
#include "Lucy/Index/TermInfo.h"
#include "Lucy/Index/TermStepper.h"
#include "Lucy/Plan/Architecture.h"
#include "Lucy/Store/Folder.h"
#include "Lucy/Store/OutStream.h"

int32_t LexWriter_current_file_format = 3;

LexiconWriter*
LexWriter_new(Schema *schema, Snapshot *snapshot, Segment *segment,
              PolyReader *polyreader) {
    LexiconWriter *self = (LexiconWriter*)VTable_Make_Obj(LEXICONWRITER);
    return LexWriter_init(self, schema, snapshot, segment, polyreader);
}

LexiconWriter*
LexWriter_init(LexiconWriter *self, Schema *schema, Snapshot *snapshot,
               Segment *segment, PolyReader *polyreader) {
    Architecture *arch = Schema_Get_Architecture(schema);

    DataWriter_init((DataWriter*)self, schema, snapshot, segment, polyreader);

    // Assign.
    self->index_interval = Arch_Index_Interval(arch);
    self->skip_interval  = Arch_Skip_Interval(arch);

    // Init.
    self->ix_out             = NULL;
    self->ixix_out           = NULL;
    self->dat_out            = NULL;
    self->count              = 0;
    self->ix_count           = 0;
    self->dat_file           = CB_new(30);
    self->ix_file            = CB_new(30);
    self->ixix_file          = CB_new(30);
    self->counts             = Hash_new(0);
    self->ix_counts          = Hash_new(0);
    self->temp_mode          = false;
    self->term_stepper       = NULL;
    self->tinfo_stepper      = (TermStepper*)MatchTInfoStepper_new(schema);

    return self;
}

void
LexWriter_destroy(LexiconWriter *self) {
    DECREF(self->term_stepper);
    DECREF(self->tinfo_stepper);
    DECREF(self->dat_file);
    DECREF(self->ix_file);
    DECREF(self->ixix_file);
    DECREF(self->dat_out);
    DECREF(self->ix_out);
    DECREF(self->ixix_out);
    DECREF(self->counts);
    DECREF(self->ix_counts);
    SUPER_DESTROY(self, LEXICONWRITER);
}

static void
S_add_last_term_to_ix(LexiconWriter *self) {
    // Write file pointer to index record.
    OutStream_Write_I64(self->ixix_out, OutStream_Tell(self->ix_out));

    // Write term and file pointer to main record.  Track count of terms added
    // to ix.
    TermStepper_Write_Key_Frame(self->term_stepper,
                                self->ix_out, TermStepper_Get_Value(self->term_stepper));
    TermStepper_Write_Key_Frame(self->tinfo_stepper,
                                self->ix_out, TermStepper_Get_Value(self->tinfo_stepper));
    OutStream_Write_C64(self->ix_out, OutStream_Tell(self->dat_out));
    self->ix_count++;
}

void
LexWriter_add_term(LexiconWriter* self, CharBuf* term_text, TermInfo* tinfo) {
    OutStream *dat_out = self->dat_out;

    if ((self->count % self->index_interval == 0)
        && !self->temp_mode
       ) {
        // Write a subset of entries to lexicon.ix.
        S_add_last_term_to_ix(self);
    }

    TermStepper_Write_Delta(self->term_stepper, dat_out, (Obj*)term_text);
    TermStepper_Write_Delta(self->tinfo_stepper, dat_out, (Obj*)tinfo);

    // Track number of terms.
    self->count++;
}

void
LexWriter_start_field(LexiconWriter *self, int32_t field_num) {
    Segment   *const segment  = LexWriter_Get_Segment(self);
    Folder    *const folder   = LexWriter_Get_Folder(self);
    Schema    *const schema   = LexWriter_Get_Schema(self);
    CharBuf   *const seg_name = Seg_Get_Name(segment);
    CharBuf   *const field    = Seg_Field_Name(segment, field_num);
    FieldType *const type     = Schema_Fetch_Type(schema, field);

    // Open outstreams.
    CB_setf(self->dat_file,  "%o/lexicon-%i32.dat",  seg_name, field_num);
    CB_setf(self->ix_file,   "%o/lexicon-%i32.ix",   seg_name, field_num);
    CB_setf(self->ixix_file, "%o/lexicon-%i32.ixix", seg_name, field_num);
    self->dat_out = Folder_Open_Out(folder, self->dat_file);
    if (!self->dat_out) { RETHROW(INCREF(Err_get_error())); }
    self->ix_out = Folder_Open_Out(folder, self->ix_file);
    if (!self->ix_out) { RETHROW(INCREF(Err_get_error())); }
    self->ixix_out = Folder_Open_Out(folder, self->ixix_file);
    if (!self->ixix_out) { RETHROW(INCREF(Err_get_error())); }

    // Initialize count and ix_count, term stepper and term info stepper.
    self->count    = 0;
    self->ix_count = 0;
    self->term_stepper = FType_Make_Term_Stepper(type);
    TermStepper_Reset(self->tinfo_stepper);
}

void
LexWriter_finish_field(LexiconWriter *self, int32_t field_num) {
    CharBuf *field = Seg_Field_Name(self->segment, field_num);

    // Store count of terms for this field as metadata.
    Hash_Store(self->counts, (Obj*)field,
               (Obj*)CB_newf("%i32", self->count));
    Hash_Store(self->ix_counts, (Obj*)field,
               (Obj*)CB_newf("%i32", self->ix_count));

    // Close streams.
    OutStream_Close(self->dat_out);
    OutStream_Close(self->ix_out);
    OutStream_Close(self->ixix_out);
    DECREF(self->dat_out);
    DECREF(self->ix_out);
    DECREF(self->ixix_out);
    self->dat_out  = NULL;
    self->ix_out   = NULL;
    self->ixix_out = NULL;

    // Close term stepper.
    DECREF(self->term_stepper);
    self->term_stepper = NULL;
}

void
LexWriter_enter_temp_mode(LexiconWriter *self, const CharBuf *field,
                          OutStream *temp_outstream) {
    Schema    *schema = LexWriter_Get_Schema(self);
    FieldType *type   = Schema_Fetch_Type(schema, field);

    // Assign outstream.
    if (self->dat_out != NULL) {
        THROW(ERR, "Can't enter temp mode (filename: %o) ", self->dat_file);
    }
    self->dat_out = (OutStream*)INCREF(temp_outstream);

    // Initialize count and ix_count, term stepper and term info stepper.
    self->count    = 0;
    self->ix_count = 0;
    self->term_stepper = FType_Make_Term_Stepper(type);
    TermStepper_Reset(self->tinfo_stepper);

    // Remember that we're in temp mode.
    self->temp_mode = true;
}

void
LexWriter_leave_temp_mode(LexiconWriter *self) {
    DECREF(self->term_stepper);
    self->term_stepper = NULL;
    DECREF(self->dat_out);
    self->dat_out   = NULL;
    self->temp_mode = false;
}

void
LexWriter_finish(LexiconWriter *self) {
    // Ensure that streams were closed (by calling Finish_Field or
    // Leave_Temp_Mode).
    if (self->dat_out != NULL) {
        THROW(ERR, "File '%o' never closed", self->dat_file);
    }
    else if (self->ix_out != NULL) {
        THROW(ERR, "File '%o' never closed", self->ix_file);
    }
    else if (self->ix_out != NULL) {
        THROW(ERR, "File '%o' never closed", self->ix_file);
    }

    // Store metadata.
    Seg_Store_Metadata_Str(self->segment, "lexicon", 7,
                           (Obj*)LexWriter_Metadata(self));
}

Hash*
LexWriter_metadata(LexiconWriter *self) {
    Hash *const metadata  = DataWriter_metadata((DataWriter*)self);
    Hash *const counts    = (Hash*)INCREF(self->counts);
    Hash *const ix_counts = (Hash*)INCREF(self->ix_counts);

    // Placeholders.
    if (Hash_Get_Size(counts) == 0) {
        Hash_Store_Str(counts, "none", 4, (Obj*)CB_newf("%i32", (int32_t)0));
        Hash_Store_Str(ix_counts, "none", 4,
                       (Obj*)CB_newf("%i32", (int32_t)0));
    }

    Hash_Store_Str(metadata, "counts", 6, (Obj*)counts);
    Hash_Store_Str(metadata, "index_counts", 12, (Obj*)ix_counts);

    return metadata;
}

void
LexWriter_add_segment(LexiconWriter *self, SegReader *reader,
                      I32Array *doc_map) {
    // No-op, since the data gets added via PostingListWriter.
    UNUSED_VAR(self);
    UNUSED_VAR(reader);
    UNUSED_VAR(doc_map);
}

int32_t
LexWriter_format(LexiconWriter *self) {
    UNUSED_VAR(self);
    return LexWriter_current_file_format;
}