// Set a breakpoint at every reachable location, as well as the return address. Without
// the benefit of an AST we can't be sure we're not at a branching statement and thus
// cannot accurately predict where we may end up.
func (thread *Thread) cnext(curpc uint64, fde *frame.FrameDescriptionEntry) error {
	pcs := thread.dbp.lineInfo.AllPCsBetween(fde.Begin(), fde.End())
	ret, err := thread.ReturnAddress()
	if err != nil {
		return err
	}
	pcs = append(pcs, ret)
	return thread.setNextTempBreakpoints(curpc, pcs)
}

// Use the AST to determine potential next lines.
func (thread *Thread) next(curpc uint64, fde *frame.FrameDescriptionEntry, file string, line int) error {
	lines, err := thread.dbp.ast.NextLines(file, line)
	if err != nil {
		if _, ok := err.(source.NoNodeError); !ok {
			return err
		}
	}

	ret, err := thread.ReturnAddress()
	if err != nil {
		return err
	}

	pcs := make([]uint64, 0, len(lines))
	for i := range lines {
		pcs = append(pcs, thread.dbp.lineInfo.AllPCsForFileLine(file, lines[i])...)
	}

	var covered bool
	for i := range pcs {
		if fde.Cover(pcs[i]) {
			covered = true
			break
		}
	}

	if !covered {
		fn := thread.dbp.goSymTable.PCToFunc(ret)
		if fn != nil && fn.Name == "runtime.goexit" {
			g, err := thread.getG()
			if err != nil {
				return err
			}
			return GoroutineExitingError{goid: g.Id}
		}
	}
	pcs = append(pcs, ret)
	return thread.setNextTempBreakpoints(curpc, pcs)
}

// Set breakpoints at every line, and the return address. Also look for
// a deferred function and set a breakpoint there too.
func (thread *Thread) next(curpc uint64, fde *frame.FrameDescriptionEntry, file string, line int) error {
	pcs := thread.dbp.lineInfo.AllPCsBetween(fde.Begin(), fde.End(), file)

	g, err := thread.GetG()
	if err != nil {
		return err
	}
	if g.DeferPC != 0 {
		f, lineno, _ := thread.dbp.goSymTable.PCToLine(g.DeferPC)
		for {
			lineno++
			dpc, _, err := thread.dbp.goSymTable.LineToPC(f, lineno)
			if err == nil {
				// We want to avoid setting an actual breakpoint on the
				// entry point of the deferred function so instead create
				// a fake breakpoint which will be cleaned up later.
				thread.dbp.Breakpoints[g.DeferPC] = new(Breakpoint)
				defer func() { delete(thread.dbp.Breakpoints, g.DeferPC) }()
				if _, err = thread.dbp.SetTempBreakpoint(dpc); err != nil {
					return err
				}
				break
			}
		}
	}

	ret, err := thread.ReturnAddress()
	if err != nil {
		return err
	}

	var covered bool
	for i := range pcs {
		if fde.Cover(pcs[i]) {
			covered = true
			break
		}
	}

	if !covered {
		fn := thread.dbp.goSymTable.PCToFunc(ret)
		if fn != nil && fn.Name == "runtime.goexit" {
			g, err := thread.GetG()
			if err != nil {
				return err
			}
			return GoroutineExitingError{goid: g.Id}
		}
	}
	pcs = append(pcs, ret)
	return thread.setNextTempBreakpoints(curpc, pcs)
}