#ifndef NOSTDLIB
	#include <stdio.h>
	#include <stdlib.h>
	#include <string.h>
	#include <ctype.h>
#endif
#include "ink.h"

#define INK_RESERVED (-1)
#define INK_FUNCTION_KW (-2)
#define INK_DO_KW (-3)
#define INK_END_KW (-4)
#define INK_LABEL (-5)
#define INK_RETURN (-6)

#define _KEYWORD_INK_FUNCTION "fn"
#define _KEYWORD_INK_DO "do"
#define _KEYWORD_INK_END "end"
#define _KEYWORD_INK_RETURN "return"

struct label {
	int active;
	int dest;
	char* name;
};

#ifdef NOSTDLIB

static size_t strlen(const char* c) {
	size_t j = 0;
	while(*(c++)) {
		j++;
	}
	return j;
}

static void* memcpy(void* _dest, const void* _src, size_t sz) {
	char* dest = _dest;
	const char* src = _src;
	while(sz--) {
		*(dest++) = *(src++);
	}
	return dest;
}

static int strcmp(const char* dest, const char* src) {
	while(*dest != 0 && *src != 0) {
		if(*(dest++) != *(src++)) {
			return 1;
		}
	}
	return 0;
}

static void* memmove(void* _dest, const void* _src, size_t sz) {
	char* dest = _dest;
	const char* src = _src;
	if (src < dest) {
		src += sz;
		dest += sz;
		while (sz-- > 0) {
			*--dest = *--src;
		}
	} else {
		while (sz-- > 0) {
			*dest++ = *src++;
		}
	}
	return dest;
}

static void* memset(void* _dest, int src, size_t sz) {
	char* dest = _dest;
	while(sz--) {
		*(dest++) = src++;
	}
	return dest;
}

static int isspace(int d) {
	return d == ' ' || d == '\t' || d == '\n';
}

static int isdigit(int d) {
	return  '0' <= d && d <= '9';
}

static int atoi(const char* c) {
	int ret = 0;
	while(*c) {
		ret *= 10;
		ret += *c - '0';
		++c;
	}
	return ret;
}

#endif

void ink_add_native(struct context* ctx, const char* name, void(*value)(struct context*)) {
	if(ctx->native_words == NULL) {
		ctx->native_words = ctx->malloc(sizeof(struct native_fn) * 8);
		ctx->native_words_top = 0;
		ctx->native_words_capacity = 8;
	} else if(ctx->native_words_top == ctx->native_words_capacity) {
		int new_count = (ctx->native_words_capacity + ctx->native_words_capacity/2);
		void* renewed = ctx->realloc(ctx->native_words, sizeof(struct native_fn) * new_count);
		if(renewed == NULL) {
			// TODO: error
		} else {
			ctx->native_words = renewed;
			ctx->native_words_capacity = new_count;
		}
	}
	int len = strlen(name);
	char* copy = ctx->malloc(len+1);
	if(copy == NULL) {
		// TODO: error
	}
	memcpy(copy, name, len);
	copy[len] = 0;
	ctx->native_words[ctx->native_words_top].value = value;
	ctx->native_words[ctx->native_words_top].name = copy;
	ctx->native_words_top++;
}

static int ink_add_indigenous(struct context* ctx, const char* name, struct elem* m, size_t count) {
	if(ctx->words == NULL) {
		ctx->words = ctx->malloc(sizeof(struct fn) * 8);
		ctx->words_top = 0;
		ctx->words_capacity = 8;
	} else if(ctx->words_top == ctx->words_capacity) {
		int new_count = (ctx->words_capacity + ctx->words_capacity/2);
		void* renewed = ctx->realloc(ctx->words, sizeof(struct native_fn) * new_count);
		if(renewed == NULL) {
			// TODO: error
		} else {
			ctx->words = renewed;
			ctx->words_capacity = new_count;
		}
	}
	int i;
	for(i = 0; i < ctx->words_top; ++i) {
		if(strcmp(name, ctx->words[i].name) == 0) {
			ctx->free(ctx->words[i].things);
			ctx->words[i].things = ctx->malloc(sizeof(struct elem) * count);
			memcpy(ctx->words[i].things, m, sizeof(struct elem) * count);
			ctx->words[i].size = count;
			return i;
		}
	}
	int len = strlen(name);
	char* copy = ctx->malloc(len+1);
	if(copy == NULL) {
		// TODO: error
	}
	memcpy(copy, name, len);
	copy[len] = 0;
	ctx->words[ctx->words_top].things = ctx->malloc(sizeof(struct elem) * count);
	memcpy(ctx->words[ctx->words_top].things, m, sizeof(struct elem) * count);
	ctx->words[ctx->words_top].size = count;
	ctx->words[ctx->words_top].name = copy;
	return ctx->words_top++;
}

static int ink_add_lex_string(struct context* ctx, const char* name) {
	int i;
	if(ctx->lex_reserved_words == NULL) {
		ctx->lex_reserved_words = ctx->malloc(sizeof(char*) * 8);
		ctx->lex_reserved_words_top = 0;
		ctx->lex_reserved_words_capacity = 8;
	} else if(ctx->lex_reserved_words_top == ctx->lex_reserved_words_capacity) {
		int new_count = (ctx->lex_reserved_words_capacity + ctx->lex_reserved_words_capacity/2);
		void* renewed = ctx->realloc(ctx->lex_reserved_words, sizeof(struct native_fn) * new_count);
		if(renewed == NULL) {
			// TODO: error
		} else {
			ctx->lex_reserved_words = renewed;
			ctx->lex_reserved_words_capacity = new_count;
		}
	}
	for(i = 0; i < ctx->lex_reserved_words_top; i++) {
		if(strcmp(ctx->lex_reserved_words[i], name) == 0) {
			return i;
		}
	}
	int len = strlen(name);
	i = ctx->lex_reserved_words_top;
	ctx->lex_reserved_words[i] = ctx->malloc(len+1);
	memcpy(ctx->lex_reserved_words[i], name, len);
	ctx->lex_reserved_words[i][len] = 0;
	ctx->lex_reserved_words_top++;
	return i;
}

void ink_push(struct context* ctx, struct elem value) {
	if(ctx->stack == NULL) {
		ctx->stack = ctx->malloc(sizeof(struct elem) * 8);
		ctx->top = 0;
		ctx->capacity = 8;
	} else if(ctx->top == ctx->capacity) {
		int new_count = (ctx->capacity + ctx->capacity/2);
		void* renewed = ctx->realloc(ctx->stack, sizeof(struct elem) * new_count);
		if(renewed == NULL) {
			// TODO: error
		} else {
			ctx->stack = renewed;
			ctx->capacity = new_count;
		}
	}
	ctx->stack[ctx->top] = value;
	ctx->top++;
}

void ink_push_fn(struct context* ctx, struct stack_frame value) {
	if(ctx->function_stack == NULL) {
		ctx->function_stack = ctx->malloc(sizeof(struct stack_frame) * 8);
		ctx->function_stack_top = 0;
		ctx->function_stack_capacity = 8;
	} else if(ctx->function_stack_top == ctx->function_stack_capacity) {
		int new_count = (ctx->function_stack_capacity + ctx->function_stack_capacity/2);
		void* renewed = ctx->realloc(ctx->function_stack, sizeof(struct stack_frame) * new_count);
		if(renewed == NULL) {
			// TODO: error
		} else {
			ctx->function_stack = renewed;
			ctx->function_stack_capacity = new_count;
		}
	}
	ctx->function_stack[ctx->function_stack_top] = value;
	ctx->function_stack_top++;
}

static void ink_pop_fn(struct context* ctx) {
	if(ctx->function_stack == NULL) return;
	if(ctx->function_stack_top == 0) return;
	ctx->function_stack_top--;
}

static void ink_pop(struct context* ctx) {
	if(ctx->stack == NULL) return;
	if(ctx->top == 0) return;
	ctx->top--;
}

struct context* ink_make_context(void*(*malloc)(size_t), void*(*realloc)(void*, size_t), void(*free)(void*), int(*putchar)(int)) {
	struct context* ctx = (struct context*)malloc(sizeof(struct context));
	ctx->malloc = malloc;
	ctx->realloc = realloc;
	ctx->free = free;
	ctx->putchar = putchar;
	ctx->panic = 0;
	ctx->stack = NULL;
	ctx->capacity = 0;
	ctx->top = 0;
	ctx->function_stack = NULL;
	ctx->function_stack_capacity = 0;
	ctx->function_stack_top = 0;
	ctx->native_words = NULL;
	ctx->native_words_capacity = 0;
	ctx->native_words_top = 0;
	ctx->words = NULL;
	ctx->words_capacity = 0;
	ctx->words_top = 0;
	ctx->lex_reserved_words = NULL;
	ctx->lex_reserved_words_capacity = 0;
	ctx->lex_reserved_words_top = 0;
	return ctx;
}

/**
 * Allocates a string that contains the integer
 * @param _ context (used to allocate)
 * @param cpy the value
 * @return the allocated string, needs to be freed by ctx->free
 */
static char* ink_itoa(struct context* _, int cpy) {
	char* n = _->malloc(16);
	n[15] = 0;
	char* it = n+15;
	do {
		it--;
		*it = (cpy % 10) + '0';
		cpy = cpy / 10;
	} while(cpy);
	memmove(n, it, 16 - (it-n));
	return n;
}

static void print_stacktrace(struct context* _) {
	int i = 0;
	for(; i < _->function_stack_top; ++i) {
		struct elem thing = _->function_stack[i].executing;
		switch(thing.type) {
			case INK_NATIVE_FUNCTION: {
				char *n = _->native_words[thing.value].name;
				while (*n) {
					_->putchar(*n);
					++n;
				}
				_->putchar(10);
				break;
			}
			case INK_FUNCTION:{
				char *n = _->native_words[thing.value].name;
				while (*n) {
					_->putchar(*n);
					++n;
				}
				_->putchar(':');
				n = ink_itoa(_, _->function_stack[i].index);
				while (*n) {
					_->putchar(*n);
					++n;
				}
				_->free(n);
				_->putchar(10);
				break;
			}
			default:
				break;
		}
	}
}

static void add_int(struct context* ctx) {
	if(ctx->top < 2) {
		ctx->panic = 1;
		return;
	}
	struct elem a =  ctx->stack[ctx->top-1];
	struct elem b =  ctx->stack[ctx->top-2];
	if(!(a.type == INK_INTEGER && b.type == INK_INTEGER)) {
		ctx->panic = 1;
		return;
	}
	ink_pop(ctx);
	ctx->stack[ctx->top-1].value = a.value + b.value;
}

static void dupe_elem(struct context* ctx) {
	if(ctx->top < 1) {
		ctx->panic = 1;
		return;
	}
	struct elem a =  ctx->stack[ctx->top-1];
	ink_push(ctx, a);
}

static void drop_elem(struct context* ctx) {
	if(ctx->top < 1) {
		ctx->panic = 1;
		return;
	}
	ink_pop(ctx);
}

static void pluck_elem(struct context* ctx) {
	if(ctx->top < 1) {
		ctx->panic = 1;
		return;
	}
	struct elem a =  ctx->stack[ctx->top-1];
	if(a.type != INK_INTEGER) {
		ctx->panic = 1;
		return;
	}
	int position = ctx->top - (a.value + 1);
	if(position >= ctx->top || position < 0) {
		ctx->panic = 1;
		return;
	}
	ink_pop(ctx);
	ink_push(ctx, ctx->stack[position]);
}

static void swap_elem(struct context* ctx) {
	if(ctx->top < 2) {
		ctx->panic = 1;
		return;
	}
	struct elem a =  ctx->stack[ctx->top-1];
	struct elem b =  ctx->stack[ctx->top-2];
	ctx->stack[ctx->top-2] = a;
	ctx->stack[ctx->top-1] = b;
}

static void return_if(struct context* ctx) {
	if(ctx->top < 1) {
		ctx->panic = 1;
		return;
	}
	struct elem a =  ctx->stack[ctx->top-1];
	if(a.type != INK_INTEGER) {
		ctx->panic = 1;
		return;
	}
	if(a.value) {
		ink_pop_fn(ctx);
		ink_pop_fn(ctx);
	}
	ink_pop(ctx);
	return;
}

static void jump_if(struct context* ctx) {
	if(ctx->top < 1) {
		ctx->panic = 1;
		return;
	}
	struct elem a = ctx->stack[ctx->top-1];
	if(a.type != INK_INTEGER) {
		ctx->panic = 1;
		return;
	}
	ink_pop(ctx);
	if(a.value) {
		ink_pop_fn(ctx);
		a = ctx->stack[ctx->top-1];
		ctx->function_stack[ctx->function_stack_top - 1].index += a.value - 3;
		ink_pop(ctx);
		//printf("\t*%d\n", ctx->function_stack[ctx->function_stack_top - 1].index);
	}
	return;
}

static void print_int(struct context* ctx) {
	if(ctx->top < 1 || ctx->stack[ctx->top-1].type != INK_INTEGER) {
		ctx->panic = 1;
		return;
	}
	struct elem a =  ctx->stack[ctx->top-1];
	ink_pop(ctx);
	char* n = ink_itoa(ctx, a.value);
	char* str = n;
	while (*str) {
		ctx->putchar(*str);
		++str;
	}
	ctx->free(n);
}

static void print_as_utf8(struct context* ctx) {
	if(ctx->top < 1 || ctx->stack[ctx->top-1].type != INK_INTEGER) {
		ctx->panic = 1;
		return;
	}
	struct elem a =  ctx->stack[ctx->top-1];
	if(a.value <= 0x7F) {
		ctx->putchar(a.value);
	} else if(a.value <= 0x7FF) {
		ctx->putchar(((a.value & 0xFC0) >> 6) | 192);
		ctx->putchar((a.value  & 0x3F) | 128);
	} else if(a.value <= 0xFFFF) {
		ctx->putchar(((a.value & 0x3F000) >> 12) | 224);
		ctx->putchar(((a.value & 0xFC0) >> 6) | 128);
		ctx->putchar((a.value  & 0x3F) | 128);
	} else if(a.value <= 0x10FFFF) {
		ctx->putchar(((a.value & 0x3C0000) >> 18)  | 240);
		ctx->putchar(((a.value & 0x3F000) >> 12) | 128);
		ctx->putchar(((a.value & 0xFC0) >> 6) | 128);
		ctx->putchar((a.value  & 0x3F) | 128);
	} else {
		ctx->panic = 1;
		return;
	}
	ink_pop(ctx);
}

#ifndef NOSTDLIB
struct context* ink_make_default_context() {
	struct context* ctx = ink_make_context(malloc, realloc, free, putchar);
	ink_add_native(ctx, "trace", print_stacktrace);
	ink_add_native(ctx, "print_int", print_int);
	ink_add_native(ctx, "print_utf8", print_as_utf8);
	ink_add_native(ctx, "+", add_int);
	ink_add_native(ctx, "swap", swap_elem);
	ink_add_native(ctx, "dup", dupe_elem);
	ink_add_native(ctx, "drop", drop_elem);
	ink_add_native(ctx, "pluck", pluck_elem);
	ink_add_native(ctx, "return_if", return_if);
	ink_add_native(ctx, "jump_if", jump_if);
	return ctx;
}
#endif

static void ink_consume_one(int* end, struct context* pContext, char** buffer, char* r) {
	int i;
	if(*end == 0) {
		return;
	}
	r[*end] = 0;
	int done = 0;
	if (strcmp(r, _KEYWORD_INK_FUNCTION) == 0) {
		struct elem value;
		value.value = 0;
		value.type = INK_FUNCTION_KW;
		ink_push(pContext, value);
		done = 1;
	}
	if (!done && strcmp(r, _KEYWORD_INK_DO) == 0) {
		struct elem value;
		value.value = 0;
		value.type = INK_DO_KW;
		ink_push(pContext, value);
		done = 1;
	}
	if (!done && strcmp(r, _KEYWORD_INK_END) == 0) {
		struct elem value;
		value.value = 0;
		value.type = INK_END_KW;
		ink_push(pContext, value);
		done = 1;
	}
	if (!done && strcmp(r, _KEYWORD_INK_RETURN) == 0) {
		struct elem value;
		value.value = 0;
		value.type = INK_RETURN;
		ink_push(pContext, value);
		done = 1;
	}
	if (!done) {
		for (i = 0; i < pContext->words_top; ++i) {
			if (strcmp(r, pContext->words[i].name) == 0) {
				struct elem value;
				value.value = i;
				value.type = INK_FUNCTION;
				ink_push(pContext, value);
				done = 1;
				break;
			}
		}
	}
	if (!done) {
		for (i = 0; i < pContext->native_words_top; ++i) {
			if (strcmp(r, pContext->native_words[i].name) == 0) {
				struct elem value;
				value.value = i;
				value.type = INK_NATIVE_FUNCTION;
				ink_push(pContext, value);
				done = 1;
				break;
			}
		}
	}
	if (!done) {
		for(i = (r[0] == '-'); i < *end; i++) {
			if(!isdigit(r[i])){
				goto not_an_int;
			}
		}
		struct elem value;
		value.value = atoi(r);
		value.type = INK_INTEGER;
		ink_push(pContext, value);
		done = 1;
	}
	not_an_int: if (!done) {
		i = ink_add_lex_string(pContext, r);
		struct elem value;
		value.value = i;
		if(r[strlen(r) - 1] == ':') {
			value.type = INK_LABEL;
		} else {
			value.type = INK_RESERVED;
		}
		ink_push(pContext, value);
	}
	*end = 0;
}

static void ink_lex(struct context *pContext, char* buffer) {
	int i;
	char r[128];
	int end = 0;
	
	while(*buffer != 0) {
		if(isspace(*buffer)) {
			ink_consume_one(&end, pContext, &buffer, r);
		} else {
			r[end] = *buffer;
			++end;
		}
		++buffer;
	}
	ink_consume_one(&end, pContext, &buffer, r);
}

static int lblcmp(const char* label, const char* other, size_t label_sz) {
	while (label_sz != 1) {
		if(*other == 0) return 1;
		if(*label != *other) return 1;
		++label;
		++other;
		label_sz--;
	}
	return 0;
}

/**
 *
 * @param pContext
 * @param executable_buffer
 * @param executable_buffer_top
 * @internal Loop from hell
 */
static void ink_parse(struct context* pContext, struct elem* executable_buffer, int* executable_buffer_top) {
	int i;
#define LABEL_BUFFER 128
#define FUNCTION_BUFFER 256
	struct label labels[LABEL_BUFFER];
	struct elem function_buffer[FUNCTION_BUFFER];
	int function_buffer_top = 0;
	int function_name = -1;
#define MODE_EXECUTABLE 0
#define MODE_FUNCTION 1
#define MODE_DO 2
	int mode = 0;
	memset(labels, 0, sizeof(struct label)*LABEL_BUFFER);
	for(i = 0; i < pContext->top; ++i) {
		struct elem current = pContext->stack[i];
		switch (mode) {
			case MODE_EXECUTABLE:
				switch(current.type) {
					case INK_FUNCTION_KW:
						mode = MODE_FUNCTION;
						goto next_token;
					case INK_DO_KW:
					case INK_END_KW:
						// TODO: error
					default:
						executable_buffer[*executable_buffer_top] = current;
						*executable_buffer_top += 1;
				}
				break;
			case MODE_FUNCTION:
				if(current.type == INK_DO_KW) {
					if(function_name == -1) {
						// TODO: error (function name was not supplied)
					} else {
						mode = MODE_DO;
						memset(labels, 0, sizeof(struct label)*128);
						goto next_token;
					}
				}
				if(function_name != -1) {
					// TODO: error (function name supplied already)
				}
				if(current.type != INK_RESERVED) {
					// TODO: error
				}
				function_name = current.value;
				break;
			case MODE_DO:
				if(current.type == INK_END_KW) {
					int j;
					for(j = 0; j < function_buffer_top; j++) {
						struct elem pt =  function_buffer[j];
						if(pt.type == INK_LABEL) {
							int k;
							for(k = 0; k < LABEL_BUFFER; k++) {
								if(labels[k].active) {
									if(strcmp(labels[k].name, pContext->lex_reserved_words[pt.value]) == 0) {
										labels[k].dest = j;
										// TODO: error
										break;
									}
								} else {
									labels[k].active = 1;
									labels[k].name = pContext->lex_reserved_words[pt.value];
									labels[k].dest = j;
									memcpy(function_buffer+j, function_buffer+j+1, sizeof(struct elem)*(function_buffer_top-j-1));
									function_buffer_top--;
									j--;
									break;
								}
							}
						}
					}
					for(j = 0; j < function_buffer_top; j++) {
						struct elem pt =  function_buffer[j];
						if(pt.type == INK_RESERVED) {
							const char* str = pContext->lex_reserved_words[pt.value];
							int k;
							for(k = 0; k < LABEL_BUFFER; k++) {
								if(labels[k].active) {
									const char* lbl = labels[k].name;
									int label_sz = strlen(lbl);
									if(lblcmp(labels[k].name, pContext->lex_reserved_words[pt.value], label_sz) == 0) {
										function_buffer[j].type = INK_INTEGER;
										function_buffer[j].value = labels[k].dest - j;
										break;
									}
								} else break;
							}
						}
					}
					ink_add_indigenous(pContext, pContext->lex_reserved_words[function_name], function_buffer, function_buffer_top);
					function_buffer_top = 0;
					mode = MODE_EXECUTABLE;
					goto next_token;
				}
				function_buffer[function_buffer_top] = current;
				function_buffer_top += 1;
				break;
		}
		next_token: i=i;
	}
	if(mode == MODE_FUNCTION || mode == MODE_DO) {
		// error, missing an end
	}
#undef MODE_EXECUTABLE
#undef MODE_FUNCTION
#undef MODE_DO

#undef LABEL_BUFFER
#undef FUNCTION_BUFFER
}

int ink_step(struct context *pContext) {
	if(pContext->function_stack_top == 0) return 0;
	if(pContext->panic) {
		return -1;
	}
	struct stack_frame* top = &pContext->function_stack[pContext->function_stack_top-1];
	switch(top->executing.type) {
		case INK_NATIVE_FUNCTION:
			if(top->index != 0) {
				ink_pop_fn(pContext);
			} else {
				top->index++;
				if(pContext->native_words_top <= top->executing.value) {
					pContext->panic = 1;
					return -1;
				}
				pContext->native_words[top->executing.value].value(pContext);
			}
			break;
		case INK_FUNCTION:
			if(pContext->words_top <= top->executing.value) {
				pContext->panic = 1;
				return -1;
			}
			if(top->index >= pContext->words[top->executing.value].size) {
				ink_pop_fn(pContext);
			} else {
				struct elem next = pContext->words[top->executing.value].things[top->index];
				if(next.type == INK_RETURN) {
					ink_pop_fn(pContext);
					return 1;
				}
				struct stack_frame frame;
				frame.executing = next;
				frame.index = 0;
				ink_push_fn(pContext, frame);
				top->index++;
			}
			break;
		default:
			ink_push(pContext, top->executing);
			ink_pop_fn(pContext);
			break;
	}
	return 1;
}

void ink_run(struct context *pContext, char* buffer) {
	pContext->free(pContext->stack);
	pContext->stack = NULL;
	pContext->top = 0;
	pContext->capacity = 0;
	ink_lex(pContext, buffer);
	int i = 0;
	struct elem executable_buffer[256];
	int executable_buffer_top = 0;
	ink_parse(pContext, executable_buffer, &executable_buffer_top);
	struct stack_frame frame;
	frame.executing.value = ink_add_indigenous(pContext, "__-MAIN-__", executable_buffer, executable_buffer_top);
	frame.executing.type = INK_FUNCTION;
	frame.index = 0;
	ink_push_fn(pContext, frame);
	
	int out;
	do {
		out = ink_step(pContext);
	} while(out > 0);
}