#include "codehighlighter.hpp"

#include "highlight-queries.hpp"

#include <tree_sitter/api.h>

#include <QHash>
#include <QMap>
#include <QVariantMap>

#include <dlfcn.h>

namespace ZShell::llm {

namespace hl {

// Role ids; 0 means "no color".
enum Role : uint8_t {
	None = 0,
	Comment,
	String,
	StringKey,
	Number,
	Constant,
	Keyword,
	Type,
	Function,
	Method,
	Macro,
	Preproc,
	Operator,
	Property,
	Label,
	Attribute,
};

const char* roleName(Role role) {
	switch (role) {
	case Comment: return "comment";
	case String: return "string";
	case StringKey: return "string.key";
	case Number: return "number";
	case Constant: return "constant";
	case Keyword: return "keyword";
	case Type: return "type";
	case Function: return "function";
	case Method: return "method";
	case Macro: return "macro";
	case Preproc: return "preproc";
	case Operator: return "operator";
	case Property: return "property";
	case Label: return "label";
	case Attribute: return "attribute";
	default: return "";
	}
}

using LanguageFn = const TSLanguage* (*)();

// Query sources, indexed by Grammar::queries.
struct QuerySources {
	std::vector<std::string> sources;
	int c, cpp, python, javascript, typescriptExtended, typescript, bash, json, rust, go, yaml, toml, sql, cppExtended;
};

const QuerySources& querySources() {
	static const QuerySources sources = [] {
		QuerySources qs;
		// javascript + typescript concatenated: the TS grammar reuses the
		// JS node names, so the JS query usually compiles against it and
		// gives full coverage; the TS-only query is the fallback.
		const std::string tsExtended =
			std::string(hq::javascript) + "\n" + std::string(hq::typescript);
		// Same for cpp: the C++ grammar is a superset of C, and the C++
		// query only covers the C++-specific delta. Base C coverage
		// (keywords, types, calls, strings, comments) comes from the C
		// query.
		const std::string cppExtended =
			std::string(hq::c) + "\n" + std::string(hq::cpp);
		qs.sources.reserve(14);
		qs.sources.push_back(hq::c);
		qs.sources.push_back(hq::cpp);
		qs.sources.push_back(hq::python);
		qs.sources.push_back(hq::javascript);
		qs.sources.push_back(tsExtended);
		qs.sources.push_back(hq::typescript);
		qs.sources.push_back(hq::bash);
		qs.sources.push_back(hq::json);
		qs.sources.push_back(hq::rust);
		qs.sources.push_back(hq::go);
		qs.sources.push_back(hq::yaml);
		qs.sources.push_back(hq::toml);
		qs.sources.push_back(hq::sql);
		qs.sources.push_back(cppExtended);
		qs.c = 0;
		qs.cpp = 1;
		qs.python = 2;
		qs.javascript = 3;
		qs.typescriptExtended = 4;
		qs.typescript = 5;
		qs.bash = 6;
		qs.json = 7;
		qs.rust = 8;
		qs.go = 9;
		qs.yaml = 10;
		qs.toml = 11;
		qs.sql = 12;
		qs.cppExtended = 13;
		return qs;
	}();
	return sources;
}

const QHash<QString, CodeHighlighter::Grammar>& grammars() {
	static const QHash<QString, CodeHighlighter::Grammar> grammars = [] {
		const auto& qs = querySources();
		QHash<QString, CodeHighlighter::Grammar> map;
		map.insert("c", {"libtree-sitter-c.so", "tree_sitter_c", {qs.c}});
		map.insert("cpp", {"libtree-sitter-cpp.so", "tree_sitter_cpp", {qs.cppExtended, qs.cpp}});
		map.insert("python", {"libtree-sitter-python.so", "tree_sitter_python", {qs.python}});
		map.insert("javascript", {"libtree-sitter-javascript.so", "tree_sitter_javascript", {qs.javascript}});
		map.insert("typescript", {"libtree-sitter-typescript.so", "tree_sitter_typescript", {qs.typescriptExtended, qs.typescript}});
		map.insert("tsx", {"libtree-sitter-tsx.so", "tree_sitter_tsx", {qs.typescriptExtended, qs.typescript}});
		map.insert("bash", {"libtree-sitter-bash.so", "tree_sitter_bash", {qs.bash}});
		map.insert("json", {"libtree-sitter-json.so", "tree_sitter_json", {qs.json}});
		map.insert("rust", {"libtree-sitter-rust.so", "tree_sitter_rust", {qs.rust}});
		map.insert("go", {"libtree-sitter-go.so", "tree_sitter_go", {qs.go}});
		map.insert("yaml", {"libtree-sitter-yaml.so", "tree_sitter_yaml", {qs.yaml}});
		map.insert("toml", {"libtree-sitter-toml.so", "tree_sitter_toml", {qs.toml}});
		map.insert("sql", {"libtree-sitter-sql.so", "tree_sitter_sql", {qs.sql}});
		return map;
	}();
	return grammars;
}

} // namespace hl

CodeHighlighter* CodeHighlighter::s_instance = nullptr;

const QHash<QString, QString>& CodeHighlighter::aliases() {
	// Language tags as written in code fences (and common variants) to
	// grammar id.
	static const QHash<QString, QString> aliases = [] {
		QHash<QString, QString> map;
		map.insert("c", "c");
		map.insert("h", "c");
		map.insert("cpp", "cpp");
		map.insert("c++", "cpp");
		map.insert("cc", "cpp");
		map.insert("cxx", "cpp");
		map.insert("h++", "cpp");
		map.insert("hpp", "cpp");
		map.insert("hh", "cpp");
		map.insert("python", "python");
		map.insert("py", "python");
		map.insert("javascript", "javascript");
		map.insert("js", "javascript");
		map.insert("jsx", "javascript");
		map.insert("mjs", "javascript");
		map.insert("cjs", "javascript");
		map.insert("typescript", "typescript");
		map.insert("ts", "typescript");
		map.insert("mts", "typescript");
		map.insert("cts", "typescript");
		map.insert("tsx", "tsx");
		map.insert("bash", "bash");
		map.insert("sh", "bash");
		map.insert("shell", "bash");
		map.insert("shellscript", "bash");
		map.insert("shell-session", "bash");
		map.insert("zsh", "bash");
		map.insert("console", "bash");
		map.insert("json", "json");
		map.insert("jsonc", "json");
		map.insert("rust", "rust");
		map.insert("rs", "rust");
		map.insert("go", "go");
		map.insert("golang", "go");
		map.insert("yaml", "yaml");
		map.insert("yml", "yaml");
		map.insert("toml", "toml");
		map.insert("sql", "sql");
		map.insert("mysql", "sql");
		map.insert("postgres", "sql");
		map.insert("postgresql", "sql");
		map.insert("sqlite", "sql");
		map.insert("sqlite3", "sql");
		return map;
	}();
	return aliases;
}

const std::vector<std::string>& CodeHighlighter::querySources() const {
	return hl::querySources().sources;
}

uint8_t CodeHighlighter::roleFor(const char* name, uint32_t length) {
	const QString n = QString::fromUtf8(name, length);
	if (n == "comment")
		return hl::Role::Comment;
	if (n.startsWith("string"))
		return n == "string.special.key" ? hl::Role::StringKey : hl::Role::String;
	if (n == "escape" || n == "regexp")
		return hl::Role::String;
	if (n.startsWith("number"))
		return hl::Role::Number;
	if (n.startsWith("constant"))
		return hl::Role::Constant;
	if (n.startsWith("keyword"))
		return hl::Role::Keyword;
	if (n == "type" || n.startsWith("type."))
		return hl::Role::Type;
	if (n == "namespace" || n == "module")
		return hl::Role::Type;
	if (n.startsWith("function") || n == "constructor")
		return hl::Role::Function;
	if (n == "method" || n == "method.builtin")
		return hl::Role::Method;
	if (n.startsWith("macro"))
		return hl::Role::Macro;
	if (n.startsWith("preproc"))
		return hl::Role::Preproc;
	if (n == "operator" || n == "punctuation.operator" || n.startsWith("operator."))
		return hl::Role::Operator;
	if (n == "property" || n == "field" || n.startsWith("property."))
		return hl::Role::Property;
	if (n == "label")
		return hl::Role::Label;
	if (n.startsWith("attribute") || n == "annotation")
		return hl::Role::Attribute;
	return hl::Role::None;
}

const char* CodeHighlighter::roleName(uint8_t role) {
	return hl::roleName(static_cast<hl::Role>(role));
}

QVariantList CodeHighlighter::highlight(const QString& code, const QString& language) const {
	QVariantList spans;
	if (code.isEmpty())
		return spans;

	const QString id = aliases().value(language.trimmed().toLower());
	if (id.isEmpty())
		return spans;
	const Grammar& grammar = hl::grammars().value(id);

	// Guard against pathological blocks; highlighting is best-effort.
	static constexpr size_t kMaxBytes = 512 * 1024;
	const QByteArray utf8 = code.toUtf8();
	if (static_cast<size_t>(utf8.size()) > kMaxBytes)
		return spans;

	State& state = m_states[id];
	if (state.bad)
		return spans;

	if (!state.lang) {
		// Missing library is retriable (it may be installed while the
		// shell runs); ABI/query failures below are not.
		state.lib = dlopen(grammar.lib.toUtf8().constData(), RTLD_NOW | RTLD_LOCAL);
		if (!state.lib)
			return spans;
		auto* symbol = reinterpret_cast<hl::LanguageFn>(
			dlsym(state.lib, grammar.symbol.toUtf8().constData()));
		if (!symbol) {
			dlclose(state.lib);
			state.lib = nullptr;
			return spans;
		}
		const TSLanguage* lang = symbol();
		const uint32_t version = ts_language_abi_version(lang);
		if (version < TREE_SITTER_MIN_COMPATIBLE_LANGUAGE_VERSION ||
		    version > TREE_SITTER_LANGUAGE_VERSION) {
			state.bad = true;
			return spans;
		}
		state.lang = lang;
	}

	if (!state.query) {
		// Candidates in priority order; first that compiles wins.
		for (const int candidate : grammar.queries) {
			const std::string& source =
				querySources()[static_cast<size_t>(candidate)];
			TSQueryError errorType = TSQueryErrorNone;
			uint32_t errorOffset = 0;
			TSQuery* query = ts_query_new(
				static_cast<const TSLanguage*>(state.lang),
				source.data(),
				static_cast<uint32_t>(source.size()),
				&errorOffset,
				&errorType);
			if (!query)
				continue;
			state.query = query;
			break;
		}
		if (!state.query) {
			state.bad = true;
			return spans;
		}
	}

	TSParser* parser = ts_parser_new();
	ts_parser_set_language(parser, static_cast<const TSLanguage*>(state.lang));
	TSTree* tree = ts_parser_parse_string(
		parser, nullptr, utf8.constData(), static_cast<uint32_t>(utf8.size()));
	if (!tree) {
		ts_parser_delete(parser);
		return spans;
	}

	TSQuery* query = static_cast<TSQuery*>(state.query);
	TSQueryCursor* cursor = ts_query_cursor_new();
	ts_query_cursor_exec(cursor, query, ts_tree_root_node(tree));

	// Per-byte winner table: captures arrive in document order and later
	// captures overwrite earlier ones (tree-sitter highlight convention).
	const uint32_t size = static_cast<uint32_t>(utf8.size());
	std::vector<uint8_t> kinds(size, 0);

	// QML slices the code by UTF-16 code unit, so spans must be in code
	// units, not bytes. cu[b] = code units before byte b.
	std::vector<uint32_t> cu(size + 1, 0);
	for (uint32_t b = 0; b < size; ++b) {
		cu[b + 1] = cu[b];
		const unsigned char c = static_cast<unsigned char>(utf8[b]);
		if (c < 0x80)
			cu[b + 1] += 1;
		else if (c < 0xC0)
			; // continuation byte
		else if (c < 0xF0)
			cu[b + 1] += 1; // 2/3-byte lead -> BMP -> one unit
		else
			cu[b + 1] += 2; // 4-byte lead -> surrogate pair
	}

	TSQueryMatch match;
	uint32_t captureIndex = 0;
	while (ts_query_cursor_next_capture(cursor, &match, &captureIndex)) {
		const TSQueryCapture& capture = match.captures[captureIndex];
		uint32_t nameLength = 0;
		const char* name = ts_query_capture_name_for_id(query, capture.index, &nameLength);
		const uint8_t role = roleFor(name, nameLength);
		if (role == 0)
			continue;
		const uint32_t start = ts_node_start_byte(capture.node);
		const uint32_t end = ts_node_end_byte(capture.node);
		if (end <= start || end > size)
			continue;
		std::fill(kinds.begin() + start, kinds.begin() + end, role);
	}

	uint32_t position = 0;
	while (position < size) {
		if (kinds[position] == 0) {
			++position;
			continue;
		}
		const uint8_t role = kinds[position];
		const uint32_t start = position;
		while (position < size && kinds[position] == role)
			++position;
		QVariantMap span;
		span.insert("start", static_cast<int>(cu[start]));
		span.insert("length", static_cast<int>(cu[position] - cu[start]));
		span.insert("kind", roleName(role));
		spans.append(span);
	}

	ts_query_cursor_delete(cursor);
	ts_tree_delete(tree);
	ts_parser_delete(parser);
	return spans;
}

CodeHighlighter* CodeHighlighter::create(QQmlEngine*, QJSEngine*) {
	if (!s_instance)
		s_instance = new CodeHighlighter();
	return s_instance;
}

} // namespace ZShell::llm