#include <cctype>

#include "kblib/convert.h"
#include "map.h"

using namespace std::string_literals;

#include "gen/cmap.inc"

const std::string_view cmaps_default{cmap_inc, sizeof(cmap_inc)};

cmap_t current_cmap = scan_cmap(cmaps_default, "__default_maps");

auto lookupMap(std::string_view query) -> unsigned {
	for (unsigned m = 0; m != current_cmap.size(); ++m) {
		if (current_cmap[m].first == query) {
			return m;
		}
	}
	return kblib::fromStr<unsigned>(query, "palette ID");
}

auto scan_cmap(std::string_view maps, std::string_view filename) -> cmap_t {
	int line{1};
	/* Format of data file:
	 *
	 * e := {empty}
	 * delim := :
	 * char := [^:]
	 * string := char* {Empty, or a char plus a string}
	 * digit := [0-9]
	 * number := digit+
	 * hexdigit := [0-9A-Fa-f]
	 * byte := hexdigit . hexdigit
	 * color := byte . byte . byte
	 * space := [ \n\t,;#]
	 * lsep := ([:punct:] | [:space:])*
	 * clist := color . space* . clist {colors may have arbitrary spacing after}
	 * cmap := string . delim . number . space+ . clist
	 *
	 * file := space* . delim . cmap . (delim . cmap)*
	 *
	 */

	const std::string_view space{" \r\n\t,;#"}, eofspace{" \r\n\t"};
	constexpr char delim{':'}, escape{'\\'};
	constexpr auto npos = std::string_view::npos;

	cmap_t out;
	std::pair<std::string, palette> working;
	std::string number, color;
	int expected{}, remaining{};
	// A clist must have as many colors as the preceding number

	// state machine:

	enum class states : uint8_t {
		Preamble,     // Start of file
		PreEscape,    //:: is an escape for :
		String,       // A cmap-name
		StringEscape, //\c in a cmap-name is replaced with c
		Number,       // A decimal number of colors to expect
		CList,        // Between colors
		HexColor,     // Reads 6 hex characters, ignores spacing chars
	} state = states::Preamble;

	for (auto c : maps) {
		if (c == '\n') {
			++line;
		}
		switch (state) {
		case states::Preamble:
			if (c == delim) {
				state = states::PreEscape;
			}
			break;
		case states::PreEscape:
			if (c == delim) {
				state = states::Preamble;
				break;
			} else {
				state = states::String;
			}
			[[fallthrough]];
		case states::String:
			if (c == escape) {
				state = states::StringEscape;
			} else if (c == delim) {
				if (not working.first.length()) {
					throw malformed_file_error{
					    kblib::concat(filename, ':', line, ": For cmap #",
					                  out.size(), ": cmap names cannot be empty")};
				}
				state = states::Number;
			} else {
				working.first += c;
			}
			break;
		case states::StringEscape:
			working.first += c;
			state = states::String;
			break;
		case states::Number:
			if (isdigit(c)) {
				number += c;
			} else if (space.find(c) != npos) {
				if (number.empty()) {
					throw malformed_file_error{kblib::concat(
					    filename, ':', line, ": For cmap #", out.size(), ": ",
					    working.first, ": ", "cmap length cannot be blank")};
				}
				state = states::CList;
				expected = remaining = kblib::parse_integer<int>(number, 10);
				number.clear();
				if (not expected) {
					throw malformed_file_error{kblib::concat(
					    filename, ':', line, ": For cmap #", out.size(), ": ",
					    working.first, ": ", "cmap length cannot be 0")};
				}
			} else {
				throw malformed_file_error{kblib::concat(
				    filename, ':', line, ": For cmap #", out.size(), ": ",
				    working.first, ": ", "encountered unexpected ", c,
				    " while reading number")};
			}
			break;
		case states::CList:
			if (isxdigit(c)) {
				color += c;
				state = states::HexColor;
			} else if (c == delim) {
				if (remaining) {
					throw malformed_file_error{kblib::concat(
					    filename, ':', line, ": For cmap #", out.size(), ": ",
					    working.first, ": ", "expected ", expected, " colors, got ",
					    expected - remaining)};
				} else {
					out.push_back(working);
					working.first.clear();
					working.second.clear();
					state = states::String;
				}
			}
			break;
		case states::HexColor:
			if (isxdigit(c)) {
				color += c;
			} else if (c == delim) {
				throw malformed_file_error{kblib::concat(
				    filename, ':', line, ": For cmap #", out.size(), ": ",
				    working.first, ": ",
				    "encountered delimiter while reading color: ", color)};
			} else if (space.find(c) == npos) {
				throw malformed_file_error{kblib::concat(
				    filename, ':', line, ": For cmap #", out.size(), ": ",
				    working.first, ": ", "illegal character in color: ", '"', color,
				    c, "\" ", +c)};
			}
			if (color.length() == 6) {
				--remaining;
				working.second.push_back(pnm::color_from_hex(color));
				color.clear();
				state = states::CList;
			}
			break;
		}
	}
	switch (state) {
	case states::Preamble:
		throw malformed_file_error{
		    kblib::concat(filename, ':', line, ": no cmaps in file")};
	case states::PreEscape:
		[[fallthrough]];
	case states::StringEscape:
		throw malformed_file_error{kblib::concat(
		    filename, ':', line, ": encountered end of file in escape")};
	case states::Number:
		throw malformed_file_error{kblib::concat(
		    filename, ':', line, ": For cmap #", out.size(), ": ", working.first,
		    ": ", "expected number, got end of file")};
	case states::HexColor:
		throw malformed_file_error{kblib::concat(
		    filename, ':', line, ": For cmap #", out.size(), ": ", working.first,
		    ": ", "encountered end of file while reading color: ", color)};
	case states::String:
		if (working.first.find_first_not_of(eofspace) != npos) {
			throw malformed_file_error{kblib::concat(
			    filename, ':', line, ": For cmap #", out.size(), ": ",
			    "encountered end of file while reading cmap-name: ",
			    working.first)};
		}
		break;
	case states::CList:
		if (remaining) {
			throw malformed_file_error{
			    kblib::concat(filename, ':', line, ": For cmap #", out.size(),
			                  ": ", working.first, ": ", "expected ", expected,
			                  " colors, got ", expected - remaining)};
		} else {
			out.push_back(working);
		}
		break;
	}
	return out;
}