#include <sys/param.h>

#include <assert.h>

#include <debug.h>

#include <memory/srealloc.h>

#include <string/new.h>
#include <string/free.h>

#include "../wcistream/struct.h"
#include "../wcistream/read.h"

#include "../position/struct.h"
#include "../position/clone.h"
#include "../position/inc.h"
#include "../position/assign.h"
#include "../position/free.h"

#include "../token/new.h"
#include "../token/inc.h"
#include "../token/free.h"

#include "struct.h"
#include "next.h"

static const enum state {
    s_error,
    
    s_EOF,
    
    s_number,
    
    s_colon,
    s_comma,
    s_equals,
    s_semicolon,
    s_oparen,
    s_cparen,
    
    s_newline,
    
    s_identifier,
    
    s_start,
    
    s_reading_newline,
    
    s_reading_slash,
    
    s_skipping_comment,
    s_skipping_comment_slash,
    
    s_reading_colon,
    s_reading_comma,
    s_reading_equals,
    s_reading_semicolon,
    s_reading_oparen,
    s_reading_cparen,
    
    s_reading_number,
    
    s_reading_identifier,
    
    number_of_states,
} lookup[number_of_states][127 + 1 + 1] = {
    
    #define ANY 0 ... 128
    
    // EOF:
    [s_start][0] = s_EOF,
    
    // skip whitespace
    [s_start][' '] = s_start,
    [s_start]['\t'] = s_start,
    [s_start]['\n'] = s_reading_newline,
        [s_reading_newline][ANY] = s_newline,
    
    // skip comments:
    [s_start]['#'] = s_skipping_comment,
        [s_skipping_comment][ANY] = s_skipping_comment,
        [s_skipping_comment]['\\'] = s_skipping_comment_slash,
            [s_skipping_comment_slash][ANY] = s_skipping_comment,
        [s_skipping_comment]['\n'] = s_start,
    
    // skip escaped newlines:
    [s_start]['\\'] = s_reading_slash,
        [s_reading_slash][ANY] = s_start,
    
    // symbols:
    [s_start][':'] = s_reading_colon,
        [s_reading_colon][ANY] = s_colon,
    [s_start][','] = s_reading_comma,
        [s_reading_comma][ANY] = s_comma,
    [s_start][';'] = s_reading_semicolon,
        [s_reading_semicolon][ANY] = s_semicolon,
    
    // brackets:
    [s_start]['('] = s_reading_oparen,
        [s_reading_oparen][ANY] = s_oparen,
    [s_start][')'] = s_reading_cparen,
        [s_reading_cparen][ANY] = s_cparen,
    
    // numeric literals:
    [s_start]['0' ... '9'] = s_reading_number,
        [s_reading_number][    ANY    ] = s_number,
        [s_reading_number]['.'] = s_reading_number,
        [s_reading_number]['0' ... '9'] = s_reading_number,
    
    // identifiers
    [s_start]['?'] = s_reading_identifier,
    [s_start]['!'] = s_reading_identifier,
    [s_start]['-'] = s_reading_identifier,
    [s_start]['>'] = s_reading_identifier,
    [s_start]['='] = s_reading_identifier,
    [s_start]['<'] = s_reading_identifier,
    [s_start]['+'] = s_reading_identifier,
    [s_start]['*'] = s_reading_identifier,
    [s_start]['_'] = s_reading_identifier,
    [s_start]['-'] = s_reading_identifier,
    [s_start]['/'] = s_reading_identifier,
    [s_start]['a' ... 'z'] = s_reading_identifier,
    [s_start]['A' ... 'Z'] = s_reading_identifier,
    [s_start][128] = s_reading_identifier,
        [s_reading_identifier][ANY] = s_identifier,
        [s_reading_identifier]['!'] = s_reading_identifier,
        [s_reading_identifier]['+'] = s_reading_identifier,
        [s_reading_identifier]['*'] = s_reading_identifier,
        [s_reading_identifier]['_'] = s_reading_identifier,
        [s_reading_identifier]['/'] = s_reading_identifier,
        [s_reading_identifier]['-'] = s_reading_identifier,
        [s_reading_identifier]['a' ... 'z'] = s_reading_identifier,
        [s_reading_identifier]['A' ... 'Z'] = s_reading_identifier,
        [s_reading_identifier]['0' ... '9'] = s_reading_identifier,
        [s_reading_identifier][128] = s_reading_identifier,
};

void tokenizer_next(
    struct tokenizer* this)
{
    ENTER;
    
    if (this->put_back)
    {
        free_token(this->token);
        
        this->token = inc_token(this->put_back);
        
        free_token(this->put_back);
        
        this->put_back = NULL;
    }
    else
    {
        this->rawtoken.n = 0;
        
        void append(wchar_t c)
        {
            ENTER;
            
            if (this->rawtoken.n == this->rawtoken.cap)
            {
                this->rawtoken.cap = this->rawtoken.cap << 1 ?: 1;
                
                this->rawtoken.data = srealloc(
                    this->rawtoken.data,
                    sizeof(*this->rawtoken.data) * this->rawtoken.cap);
            }
            
            this->rawtoken.data[this->rawtoken.n++] = c;
            
            EXIT;
        }
        
        struct position* start_position = clone_position(this->position);
        struct position* end_position = this->position;
        
        enum state state = s_start;
        
        while (state >= s_start)
        {
            dpvu(this->stream->wc);
            dpvwc(this->stream->wc);
            
            state = lookup[state][MIN(this->stream->wc, 128)];
            
            if (state > s_start)
            {
                append(this->stream->wc);
                
                switch (this->stream->wc)
                {
                    case '\t': end_position->column += 4; break;
                    
                    case '\n': end_position->line++, end_position->column = 1; break;
                    
                    default: end_position->column++; break;
                }
                
                wcistream_read(this->stream);
            }
            
            if (state == s_start)
            {
                this->rawtoken.n = 0;
                
                assign_position(start_position, end_position);
                
                wcistream_read(this->stream);
            }
        }
        
        append(0), this->rawtoken.n--;
        
        free_token(this->token), this->token = NULL;
        
        struct position* end_clone = clone_position(end_position);
        
        switch (state)
        {
            case s_error:
            {
                dpvws(this->rawtoken.data);
                
                TODO;
                
                break;
            }
            
            case s_EOF:
            {
                this->token = new_token(
                    /* kind: */ tk_EOF,
                    /* text: */ NULL,
                    /* start position: */ end_clone,
                    /* end position: */ end_clone);
                
                break;
            }
            
            case s_newline:
            {
                struct string* text = new_string(
                    /* data: */ this->rawtoken.data,
                    /*  len: */ this->rawtoken.n);
                
                this->token = new_token(
                    /* kind: */ tk_newline,
                    /* text: */ text,
                    /* start position: */ start_position,
                    /* end position: */ end_clone);
                
                free_string(text);
                
                break;
            }
            
            case s_identifier:
            {
                dpvws(this->rawtoken.data);
                
                struct string* text = new_string(
                    /* data: */ this->rawtoken.data,
                    /*  len: */ this->rawtoken.n);
                
                if (!wcscmp(this->rawtoken.data, L"λ"))
                {
                    this->token = new_token(
                        /* kind: */ tk_lambda,
                        /* text: */ text,
                        /* start position: */ start_position,
                        /* end position: */ end_clone);
                }
                else if (!wcscmp(this->rawtoken.data, L"<-"))
                {
                    this->token = new_token(
                        /* kind: */ tk_arrow,
                        /* text: */ text,
                        /* start position: */ start_position,
                        /* end position: */ end_clone);
                }
                else
                {
                    this->token = new_token(
                        /* kind: */ tk_identifier,
                        /* text: */ text,
                        /* start position: */ start_position,
                        /* end position: */ end_clone);
                }
                
                free_string(text);
                
                break;
            }
            
            case s_colon:
            {
                struct string* text = new_string(
                    /* data: */ this->rawtoken.data,
                    /*  len: */ this->rawtoken.n);
                
                this->token = new_token(
                    /* kind: */ tk_colon,
                    /* text: */ text,
                    /* start position: */ start_position,
                    /* end position: */ end_clone);
                
                free_string(text);
                
                break;
            }
            
            case s_comma:
            {
                struct string* text = new_string(
                    /* data: */ this->rawtoken.data,
                    /*  len: */ this->rawtoken.n);
                
                this->token = new_token(
                    /* kind: */ tk_comma,
                    /* text: */ text,
                    /* start position: */ start_position,
                    /* end position: */ end_clone);
                
                free_string(text);
                
                break;
            }
            
            case s_semicolon:
            {
                struct string* text = new_string(
                    /* data: */ this->rawtoken.data,
                    /*  len: */ this->rawtoken.n);
                
                this->token = new_token(
                    /* kind: */ tk_semicolon,
                    /* text: */ text,
                    /* start position: */ start_position,
                    /* end position: */ end_clone);
                
                free_string(text);
                
                break;
            }
            
            case s_oparen:
            {
                struct string* text = new_string(
                    /* data: */ this->rawtoken.data,
                    /*  len: */ this->rawtoken.n);
                
                this->token = new_token(
                    /* kind: */ tk_oparen,
                    /* text: */ text,
                    /* start position: */ start_position,
                    /* end position: */ end_clone);
                
                free_string(text);
                
                break;
            }
            
            case s_cparen:
            {
                struct string* text = new_string(
                    /* data: */ this->rawtoken.data,
                    /*  len: */ this->rawtoken.n);
                
                this->token = new_token(
                    /* kind: */ tk_cparen,
                    /* text: */ text,
                    /* start position: */ start_position,
                    /* end position: */ end_clone);
                
                free_string(text);
                
                break;
            }
            
            case s_number:
            {
                struct string* text = new_string(
                    /* data: */ this->rawtoken.data,
                    /*  len: */ this->rawtoken.n);
                
                this->token = new_token(
                    /* kind: */ tk_literal,
                    /* text: */ text,
                    /* start position: */ start_position,
                    /* end position: */ end_clone);
                
                free_string(text);
                
                break;
            }
            
            default:
                TODO;
                break;
        }
        
        free_position(start_position);
        
        free_position(end_clone);
    }
    
    EXIT;
}