//! Module graph pretty printer using S-expression syntax.

use std::fmt;

use std::mem;

use std::io;

use std::lang::sexpr;

use std::lang::alloc;

/// Format a u32 and allocate the result in the arena.

unsafe fn formatId(a: &mut alloc::Arena, id: u32) -> *[u8] {

    let mut digits: [u8; 10] = undefined;

    let start = fmt::formatU32(id, &mut digits[..]);

    let ptr = try alloc::allocSlice(a, 1, 1, digits.len - start) catch { return "?"; };

    let slice = ptr as *mut [u8];

    try mem::copy(slice, &digits[start..]) catch { return "?"; };

    return slice;

}

/// Convert a module state into an S-expression symbol.

fn stateToExpr(state: super::ModuleState) -> sexpr::Expr {

    match state {

        case super::ModuleState::Vacant => return sexpr::sym("vacant"),

        case super::ModuleState::Registered => return sexpr::sym("registered"),

        case super::ModuleState::Parsing => return sexpr::sym("parsing"),

        case super::ModuleState::Parsed => return sexpr::sym("parsed"),

        case super::ModuleState::Analyzing => return sexpr::sym("analyzing"),

        case super::ModuleState::Ready => return sexpr::sym("ready"),

    }

}

/// Recursively convert a module entry and its descendants to an S-expression.

unsafe fn subtreeToExpr(

    a: &mut alloc::Arena,

    graph: &super::ModuleGraph,

    entry: *super::ModuleEntry

) -> sexpr::Expr {

    let idText = formatId(a, entry.id as u32);

    let path = super::moduleQualifiedPath(entry);

    let mut pathBuf: *[sexpr::Expr] = &[];

    if path.len > 0 {

        let buf = try! sexpr::allocExprs(a, path.len);

        for seg, i in path { set buf[i] = sexpr::sym(seg); }

        set pathBuf = buf;

    }

    let mut childBuf: *[sexpr::Expr] = &[];

    let childCount = super::childCount(entry);

    if childCount > 0 {

        let buf = try! sexpr::allocExprs(a, childCount);

        for i in 0..childCount {

            if let child = super::get(graph, super::childAt(entry, i)) {

                set buf[i] = subtreeToExpr(a, graph, child);

            }

        }

        set childBuf = buf;

    }

    return sexpr::block(a, "module", &[

        sexpr::sym(entry.name),

        sexpr::list(a, "id", &[sexpr::sym(idText)]),

        sexpr::list(a, "state", &[stateToExpr((*entry.updates).state)]),

        sexpr::Expr::Str(entry.filePath),

        sexpr::Expr::List { head: "::", tail: pathBuf, multiline: false }

    ], childBuf);

}

/// Print the entire module graph in S-expression format.

export unsafe fn printGraph(graph: &super::ModuleGraph, arena: &mut alloc::Arena) {

    // Print all root modules.

    for i in 0..graph.entriesLen {

        let entry = super::get(graph, i as u16) else panic;

        if entry.parent == nil {

            sexpr::print(subtreeToExpr(arena, graph, entry), 0);

            io::print("\n");

        }

    }

}