#include <iostream>

#include "globals.hh"
#include "store.hh"
#include "fstate.hh"
#include "archive.hh"
#include "shared.hh"


typedef void (* Operation) (Strings opFlags, Strings opArgs);


typedef enum { atpHash, atpPath, atpUnknown } ArgType;

static ArgType argType = atpUnknown;


/* Nix syntax:

   nix [OPTIONS...] [ARGUMENTS...]

   Operations:

     --install / -i: realise an fstate
     --delete / -d: delete paths from the Nix store
     --add / -A: copy a path to the Nix store
     --query / -q: query information

     --substitute: register a substitute expression

     --dump: dump a path as a Nix archive
     --restore: restore a path from a Nix archive

     --init: initialise the Nix database
     --verify: verify Nix structures

     --version: output version information
     --help: display help

   Source selection for --install, --dump:

     --file / -f: by file name  !!! -> path
     --hash / -h: by hash

   Query flags:

     --path / -p: query the path of an fstate 
     --refs / -r: query paths referenced by an fstate

   Options:

     --verbose / -v: verbose operation
*/


/* Parse the `-f' / `-h' / flags, i.e., the type of arguments.  These
   flags are deleted from the referenced vector. */
static void getArgType(Strings & flags)
{
    for (Strings::iterator it = flags.begin();
         it != flags.end(); )
    {
        string arg = *it;
        ArgType tp;
        if (arg == "--hash" || arg == "-h") tp = atpHash;
        else if (arg == "--file" || arg == "-f") tp = atpPath;
        else { it++; continue; }
        if (argType != atpUnknown)
            throw UsageError("only one argument type specified may be specified");
        argType = tp;
        it = flags.erase(it);
    }
    if (argType == atpUnknown)
        throw UsageError("argument type not specified");
}


static Hash argToHash(const string & arg)
{
    if (argType == atpHash)
        return parseHash(arg);
    else if (argType == atpPath) {
        string path;
        Hash hash;
        addToStore(arg, path, hash);
        return hash;
    }
    else abort();
}


/* Realise (or install) paths from the given Nix fstate
   expressions. */
static void opInstall(Strings opFlags, Strings opArgs)
{
    getArgType(opFlags);
    if (!opFlags.empty()) throw UsageError("unknown flag");

    for (Strings::iterator it = opArgs.begin();
         it != opArgs.end(); it++)
    {
        StringSet paths;
        realiseFState(hash2fstate(argToHash(*it)), paths);
    }
}


/* Delete a path in the Nix store directory. */
static void opDelete(Strings opFlags, Strings opArgs)
{
    if (!opFlags.empty()) throw UsageError("unknown flag");

    for (Strings::iterator it = opArgs.begin();
         it != opArgs.end(); it++)
        deleteFromStore(absPath(*it));
}


/* Add paths to the Nix values directory and print the hashes of those
   paths. */
static void opAdd(Strings opFlags, Strings opArgs)
{
    getArgType(opFlags);
    if (!opFlags.empty()) throw UsageError("unknown flag");

    for (Strings::iterator it = opArgs.begin();
         it != opArgs.end(); it++)
    {
        string path;
        Hash hash;
        addToStore(*it, path, hash);
        cout << format("%1% %2%\n") % (string) hash % path;
    }
}


/* Perform various sorts of queries. */
static void opQuery(Strings opFlags, Strings opArgs)
{
    enum { qPath, qRefs, qUnknown } query = qPath;

    for (Strings::iterator it = opFlags.begin();
         it != opFlags.end(); )
    {
        string arg = *it;
        if (arg == "--path" || arg == "-p") query = qPath;
        else if (arg == "--refs" || arg == "-r") query = qRefs;
        else { it++; continue; }
        it = opFlags.erase(it);
    }

    getArgType(opFlags);
    if (!opFlags.empty()) throw UsageError("unknown flag");

    for (Strings::iterator it = opArgs.begin();
         it != opArgs.end(); it++)
    {
        Hash hash = argToHash(*it);

        switch (query) {

        case qPath: {
            StringSet refs;
            cout << format("%s\n") % 
                (string) fstatePath(realiseFState(termFromHash(hash), refs));
            break;
        }

        case qRefs: {
            StringSet refs;
            FState fs = hash2fstate(hash);
            fstateRefs(realiseFState(fs, refs), refs);
            for (StringSet::iterator j = refs.begin(); 
                 j != refs.end(); j++)
                cout << format("%s\n") % *j;
            break;
        }

        default:
            abort();
        }
    }
}


static void opSubstitute(Strings opFlags, Strings opArgs)
{
    if (!opFlags.empty()) throw UsageError("unknown flag");
    if (opArgs.size() % 2) throw UsageError("expecting even number of arguments");
    
    for (Strings::iterator i = opArgs.begin();
         i != opArgs.end(); )
    {
        Hash srcHash = parseHash(*i++);
        Hash subHash = parseHash(*i++);
        registerSubstitute(srcHash, subHash);
    }
}


/* A sink that writes dump output to stdout. */
struct StdoutSink : DumpSink
{
    virtual void operator ()
        (const unsigned char * data, unsigned int len)
    {
        if (write(STDOUT_FILENO, (char *) data, len) != (ssize_t) len)
            throw SysError("writing to stdout");
    }
};


/* Dump a path as a Nix archive.  The archive is written to standard
   output. */
static void opDump(Strings opFlags, Strings opArgs)
{
    getArgType(opFlags);
    if (!opFlags.empty()) throw UsageError("unknown flag");
    if (opArgs.size() != 1) throw UsageError("only one argument allowed");

    StdoutSink sink;
    string arg = *opArgs.begin();
    string path;
    
    if (argType == atpHash) path = expandHash(parseHash(arg));
    else if (argType == atpPath) path = arg;

    dumpPath(path, sink);
}


/* A source that read restore intput to stdin. */
struct StdinSource : RestoreSource
{
    virtual void operator () (const unsigned char * data, unsigned int len)
    {
        ssize_t res = read(STDIN_FILENO, (char *) data, len);
        if (res == -1)
            throw SysError("reading from stdin");
        if (res != (ssize_t) len)
            throw Error("not enough data available on stdin");
    }
};


/* Restore a value from a Nix archive.  The archive is written to
   standard input. */
static void opRestore(Strings opFlags, Strings opArgs)
{
    if (!opFlags.empty()) throw UsageError("unknown flag");
    if (opArgs.size() != 1) throw UsageError("only one argument allowed");

    StdinSource source;
    restorePath(*opArgs.begin(), source);
}


/* Initialise the Nix databases. */
static void opInit(Strings opFlags, Strings opArgs)
{
    if (!opFlags.empty()) throw UsageError("unknown flag");
    if (!opArgs.empty())
        throw UsageError("--init does not have arguments");
    initDB();
}


/* Scan the arguments; find the operation, set global flags, put all
   other flags in a list, and put all other arguments in another
   list. */
void run(Strings args)
{
    Strings opFlags, opArgs;
    Operation op = 0;

    for (Strings::iterator it = args.begin();
         it != args.end(); it++)
    {
        string arg = *it;

        Operation oldOp = op;

        if (arg == "--install" || arg == "-i")
            op = opInstall;
        else if (arg == "--delete" || arg == "-d")
            op = opDelete;
        else if (arg == "--add" || arg == "-A")
            op = opAdd;
        else if (arg == "--query" || arg == "-q")
            op = opQuery;
        else if (arg == "--substitute")
            op = opSubstitute;
        else if (arg == "--dump")
            op = opDump;
        else if (arg == "--restore")
            op = opRestore;
        else if (arg == "--init")
            op = opInit;
        else if (arg[0] == '-')
            opFlags.push_back(arg);
        else
            opArgs.push_back(arg);

        if (oldOp && oldOp != op)
            throw UsageError("only one operation may be specified");
    }

    if (!op) throw UsageError("no operation specified");

    op(opFlags, opArgs);
}


string programId = "nix";