#include <u.h>
#include <libn.h>
#include <libbio.h>

// -----------------------------------------------------------------------
// Tokens

enum TokenKind
{
    tok·nil,
    tok·eof,
    tok·space,
    tok·ident,
    tok·number,
    tok·lparen,
    tok·rparen,
    tok·lbrak,
    tok·rbrak,
    tok·comma,
    tok·semi,
    tok·colon,

    NUM_TOKENS,
};


struct Token {
    enum TokenKind kind;
    union 
    {
        byte  *s;
        double x;
    } lit;
};

byte*
tokstr(struct Token tok)
{
    static byte b[50];
    switch (tok.kind) {
       case tok·nil:    return ""; 
       case tok·eof:    return nil;
       case tok·space:  return " ";
       case tok·ident:  return tok.lit.s;
       case tok·lparen: return "(";
       case tok·rparen: return ")";
       case tok·lbrak:  return "[";
       case tok·rbrak:  return "]";
       case tok·comma:  return ",";
       case tok·semi:   return ";";
       case tok·colon:  return ":";
       case tok·number: 
            snprintf(b, arrlen(b), "%f", tok.lit.x);
            return b;
        default:
            return nil;
    }
}


// -----------------------------------------------------------------------
// Read

// TODO: Bounds checking on buffer
struct Token
lex(Stream *s)
{
    struct Token tok;
    byte *c, b[1024];
    c  = b;
    *c = io·getbyte(s);

    if (isspace(*c)) {
        while (isspace(*c)) {
            *(++c) = io·getbyte(s);
        }

        io·ungetbyte(s, *c);
        Assert(c - b < 1024);

        *c        = 0;
        tok.kind  = tok·space;
        tok.lit.s = b;
        return tok;
    }

    switch (*c) {
    case EOF: tok.kind = tok·eof;    return tok;
    case '(': tok.kind = tok·lparen; return tok;
    case ')': tok.kind = tok·rparen; return tok;
    case '[': tok.kind = tok·lbrak;  return tok;
    case ']': tok.kind = tok·rbrak;  return tok;
    case ',': tok.kind = tok·comma;  return tok;
    case ';': tok.kind = tok·semi;   return tok;
    case ':': tok.kind = tok·colon;  return tok;

    case '.':
    case '0': case '1': case '2': case '3': case '4':
    case '5': case '6': case '7': case '8': case '9':
        while (isdigit(*c)) {
    NUM:    *(++c) = io·getbyte(s);
        }
        if (*c == '.') goto NUM;

        io·ungetbyte(s, *c);
        Assert(c - b < 1024);

        *c        = 0;
        tok.kind  = tok·number;
        tok.lit.x = atof(b);
        return tok;

    default:
        while (isalnum(*c)) {
            *(++c) = io·getbyte(s);
        }

        io·ungetbyte(s, *c);
        Assert(c - b < 1024);

        *c        = 0;
        tok.kind  = tok·ident;
        tok.lit.s = b;
        return tok;
    }
}

struct Token
lex_nospace(Stream *s)
{
    struct Token tok;
    tok = lex(s);
    if (tok.kind == tok·space) {
        lex_nospace(s);
    }

    return tok;
}

struct Parser
{
    int          lev;
    bio·Node    *root;
    struct Token tok;

    Stream       *file;
    mem·Allocator heap;
};

error
parse(struct Parser *p)
{
    error err;
    bio·Node *node;
    bio·Node *root;
    struct Token tok;

    for (;;) {
        tok = lex_nospace(p->file);

        switch (tok.kind) {
        case tok·lparen:
            if (p->lev > 0) {
                errorf("incorrect format: opening another node before termination of last tree\n");
                goto ERROR;
            }
            node = p->heap.alloc(sizeof(*node));
            memset(node, 0, sizeof(*node));
            if (p->root) {
                phylo·addchild(p->root, node);
                root = p->root;
            } else {
                root = node;
            }

            p->lev++;
            err = parse(p);
            if (err) {
                goto ERROR;
            }
            if (p->tok.kind != tok·rparen) {
                errorf("incorrect format: closing parentheses expected to proceed opening\n");
                goto ERROR;
            }
            p->root = root;

        break;

        case tok·rparen:
            p->lev--;
            goto DONE;

        /* Comments */
        case tok·lbrak:
            if (!node) {
                errorf("incorrect format: comment found in disallowed region\n");
                goto ERROR;
            }
            node->comment = str·new("");
            while (tok.kind != tok·rbrak) {
                tok = lex_nospace(p->file);
                if (tok.kind == tok·eof || tok.kind == tok·nil) {
                    errorf("incorrect format: unmatched comment bracket '['\n");
                    goto ERROR;
                }
                str·append(node->comment, tokstr(tok));
            }
        break;

        case tok·rbrak:
           errorf("incorrect format: end comment token found in disallowed region\n");
           goto ERROR;
        break;

        case tok·colon:
            tok = lex_nospace(p->file);
            if (tok.kind != tok·number) {
                errorf("incorrect format: expected number after colon\n");
                goto ERROR;
            }
            if (node == nil) {
                errorf("parse error: attempting to set distance of nil node\n");
                goto ERROR;
            }
            node->dist = tok.lit.x;
        break;

        case tok·comma:
            node = nil;
        break;

        case tok·ident:
            if (p->tok.kind != tok·rparen) {
                if (!node) {
                    errorf("parse error: attempting to set name of nil node\n");
                    goto ERROR;
                }
                node->name = str·new(tok.lit.s);
            } else {
                if (p->tok.kind != tok·comma) {
                    errorf("format error: misplaced identifier found\n");
                    goto ERROR;
                }
                if (!node) {
                    errorf("parse error: attempting to create child for no parent\n");
                    goto ERROR;
                }
                node = p->heap.alloc(sizeof(*node));
                memset(node, 0, sizeof(*node));
                phylo·addchild(p->root, node);
            }
        break;

        case tok·number:
            if (p->tok.kind == tok·rparen) {
                if (p->lev == 0) {
                    errorf("format error: support value on root not supported\n");
                    goto ERROR;
                }
                node->support = tok.lit.x;
            } else {
                errorf("format error: found number in unexpected location\n");
                goto ERROR;
            }
        break;

        case tok·semi:
            io·ungetbyte(p->file, ';');
            if (p->lev) {
                errorf("format error: uneven number of parentheses found at ';'\n");
            }
            goto DONE;
        break;

        case tok·eof:
            goto DONE;
        break;

        default: 
            goto ERROR;
        }

        p->tok = tok;
    }


DONE:
    p->tok = tok;
    return 0;
ERROR:
    // TODO(nnoll): cleanup
    return 1;
}

bio·Tree
bio·readnewick(Stream *file, mem·Allocator heap)
{
    error err;
    struct Parser p;
    bio·Tree tree;

    err = parse(&p);
    if (err) {
        errorf("parsing failed\n");
        return tree;
    }
    tree.root = p.root;

    return tree;
}

// -----------------------------------------------------------------------
// Write