#include "GoHighlighter.h"
#include "Buffer.h"
#include <cctype>

namespace kte {

static void push(std::vector<HighlightSpan> &out, int a, int b, TokenKind k){ if (b>a) out.push_back({a,b,k}); }
static bool is_ident_start(char c){ return std::isalpha(static_cast<unsigned char>(c)) || c=='_'; }
static bool is_ident_char(char c){ return std::isalnum(static_cast<unsigned char>(c)) || c=='_'; }

GoHighlighter::GoHighlighter()
{
    const char* kw[] = {"break","case","chan","const","continue","default","defer","else","fallthrough","for","func","go","goto","if","import","interface","map","package","range","return","select","struct","switch","type","var"};
    for (auto s: kw) kws_.insert(s);
    const char* tp[] = {"bool","byte","complex64","complex128","error","float32","float64","int","int8","int16","int32","int64","rune","string","uint","uint8","uint16","uint32","uint64","uintptr"};
    for (auto s: tp) types_.insert(s);
}

void GoHighlighter::HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const
{
    const auto &rows = buf.Rows();
    if (row < 0 || static_cast<std::size_t>(row) >= rows.size()) return;
    std::string s = static_cast<std::string>(rows[static_cast<std::size_t>(row)]);
    int n = static_cast<int>(s.size());
    int i = 0;
    int bol=0; while (bol<n && (s[bol]==' '||s[bol]=='\t')) ++bol;
    // line comment
    while (i < n) {
        char c = s[i];
        if (c==' '||c=='\t') { int j=i+1; while (j<n && (s[j]==' '||s[j]=='\t')) ++j; push(out,i,j,TokenKind::Whitespace); i=j; continue; }
        if (c=='/' && i+1<n && s[i+1]=='/') { push(out,i,n,TokenKind::Comment); break; }
        if (c=='/' && i+1<n && s[i+1]=='*') {
            int j=i+2; bool closed=false; while (j+1<=n) { if (j+1<n && s[j]=='*' && s[j+1]=='/') { j+=2; closed=true; break; } ++j; }
            if (!closed) { push(out,i,n,TokenKind::Comment); break; } else { push(out,i,j,TokenKind::Comment); i=j; continue; }
        }
        if (c=='"' || c=='`') {
            char q=c; int j=i+1; bool esc=false; if (q=='`') { while (j<n && s[j] != '`') ++j; if (j<n) ++j; }
            else { while (j<n){ char d=s[j++]; if (esc){esc=false; continue;} if (d=='\\'){esc=true; continue;} if (d=='"') break;} }
            push(out,i,j,TokenKind::String); i=j; continue;
        }
        if (std::isdigit(static_cast<unsigned char>(c))) { int j=i+1; while (j<n && (std::isalnum(static_cast<unsigned char>(s[j]))||s[j]=='.'||s[j]=='x'||s[j]=='X'||s[j]=='_')) ++j; push(out,i,j,TokenKind::Number); i=j; continue; }
        if (is_ident_start(c)) { int j=i+1; while (j<n && is_ident_char(s[j])) ++j; std::string id=s.substr(i,j-i); TokenKind k=TokenKind::Identifier; if (kws_.count(id)) k=TokenKind::Keyword; else if (types_.count(id)) k=TokenKind::Type; push(out,i,j,k); i=j; continue; }
        if (std::ispunct(static_cast<unsigned char>(c))) { TokenKind k=TokenKind::Operator; if (c==';'||c==','||c=='('||c==')'||c=='{'||c=='}'||c=='['||c==']') k=TokenKind::Punctuation; push(out,i,i+1,k); ++i; continue; }
        push(out,i,i+1,TokenKind::Default); ++i;
    }
}

} // namespace kte