(**************************************************************************)
(*                                                                        *)
(*    Copyright 2012-2020 OCamlPro                                        *)
(*    Copyright 2012 INRIA                                                *)
(*                                                                        *)
(*  All rights reserved. This file is distributed under the terms of the  *)
(*  GNU Lesser General Public License version 2.1, with the special       *)
(*  exception on linking described in the file LICENSE.                   *)
(*                                                                        *)
(**************************************************************************)

open OpamTypes
open OpamTypesBase
open OpamPackage.Set.Op

let log ?level fmt = OpamConsole.log ?level "SOLVER" fmt
let slog = OpamConsole.slog

module Action = OpamActionGraph.MakeAction(OpamPackage)
module ActionGraph = OpamActionGraph.Make(Action)
type solution = OpamCudf.ActionGraph.t

let empty_universe =
  {
    u_packages = OpamPackage.Set.empty;
    u_installed = OpamPackage.Set.empty;
    u_available = lazy OpamPackage.Set.empty;
    u_depends = OpamPackage.Map.empty;
    u_depopts = OpamPackage.Map.empty;
    u_conflicts = OpamPackage.Map.empty;
    u_action = Install;
    u_installed_roots = OpamPackage.Set.empty;
    u_pinned = OpamPackage.Set.empty;
    u_invariant = OpamFormula.Empty;
    u_reinstall = OpamPackage.Set.empty;
    u_attrs = [];
  }

let solution_to_json solution =
  OpamCudf.ActionGraph.to_json solution
let solution_of_json json =
  OpamCudf.ActionGraph.of_json json

let cudf_versions_map universe =
  log ~level:3 "cudf_versions_map";
  let add_packages_from_formula acc formula =
    List.fold_left (fun acc -> function
        | n, Some (_, v) -> OpamPackage.Set.add (OpamPackage.create n v) acc
        | _, None -> acc)
      acc (OpamFormula.atoms formula)
  in
  let add_referred_to_packages filt acc refmap =
    OpamPackage.Map.fold (fun _ deps acc ->
        add_packages_from_formula acc (filt deps))
      refmap acc
  in
  let filt f =
    OpamFilter.filter_deps ~build:true ~post:true ~default:false f
  in
  let id = fun x -> x in
  let packages = universe.u_packages ++ universe.u_installed in
  let packages = add_referred_to_packages filt packages universe.u_depends in
  let packages = add_referred_to_packages filt packages universe.u_depopts in
  let packages = add_referred_to_packages id packages universe.u_conflicts in
  let packages = add_packages_from_formula packages universe.u_invariant in
  let pmap = OpamPackage.to_map packages in
  OpamPackage.Name.Map.fold (fun name versions acc ->
      let _, map =
        OpamPackage.Version.Set.fold
          (fun version (i,acc) ->
             let nv = OpamPackage.create name version in
             i + 1, OpamPackage.Map.add nv i acc)
          versions (1,acc) in
      map)
    pmap OpamPackage.Map.empty

let name_to_cudf name =
  let name_s = OpamPackage.Name.to_string name in
  if OpamStd.String.for_all (function
      | 'a'..'z' | 'A'..'Z' | '0'..'9' | '@' | '/' | '+' | '(' | ')' | '.' | '-'
        -> true
      | _ -> false)
      name_s
  then name_s
  else Dose_common.CudfAdd.encode name_s

let constraint_to_cudf version_map name (op,v) =
  let nv = OpamPackage.create name v in
  try
    Some (op, OpamPackage.Map.find nv version_map)
  with Not_found ->
    (* The version for comparison doesn't exist: match to the closest
       existing version according to the direction of the comparison
       (this shouldn't happen for any constraint in the universe, now that we
       compute a full version map, but may still happen for user-provided
       constraints) *)
    log "Warn: fallback constraint for %s"
      (OpamFormula.string_of_atom (name, Some (op,v)));
    let all_versions =
      OpamPackage.Map.filter (fun nv _ -> nv.name = name)
        version_map in
    match op with
    | `Neq -> None (* Always true *)
    | `Eq -> (* Always false *)
      Some (`Gt, OpamPackage.Map.cardinal all_versions)
    | (`Geq | `Gt | `Leq | `Lt) as op ->
      let sign, result_op =  match op with
        | `Geq | `Gt -> (fun x -> x), `Geq
        | `Leq | `Lt -> (fun x -> -x), `Leq in
      let rev_version_map =
        OpamPackage.Map.fold (fun nv cv acc ->
            OpamStd.IntMap.add (sign cv) nv.version acc)
          all_versions OpamStd.IntMap.empty in
      let map =
        OpamStd.IntMap.filter
          (fun _ v1 -> sign (OpamPackage.Version.compare v v1) < 0)
          rev_version_map in
      if OpamStd.IntMap.is_empty map then
        match result_op with
        | `Geq -> Some (`Gt, max 1 (OpamPackage.Map.cardinal all_versions))
        | `Leq -> Some (`Lt, 1)
      else Some (result_op, sign (fst (OpamStd.IntMap.min_binding map)))

let atom2cudf _universe (version_map : int OpamPackage.Map.t) (name,cstr) =
  name_to_cudf name,
  OpamStd.Option.Op.(cstr >>= constraint_to_cudf version_map name)

let opam_constraint_package version_map deps label package =
  let depends =
    deps
    |> OpamFormula.map (fun at -> Atom (atom2cudf () version_map at))
    |> OpamFormula.cnf_of_formula
    |> OpamFormula.ands_to_list
    |> List.map (OpamFormula.fold_right (fun acc x -> x::acc) [])
  in {
    Cudf.
    package = fst package;
    version = snd package;
    depends;
    conflicts = [];
    provides = [];
    installed = true;
    was_installed = true;
    keep = `Keep_version;
    pkg_extra = [
      OpamCudf.s_source, `String label;
      OpamCudf.s_source_number, `String "NULL";
    ];
  }

let opam_invariant_package version_map deps =
  opam_constraint_package version_map (OpamFormula.to_atom_formula deps)
    "SWITCH_INVARIANT"
    OpamCudf.opam_invariant_package

let opam_deprequest_package version_map deps =
  opam_constraint_package version_map deps
    "DEP_REQUEST"
    OpamCudf.opam_deprequest_package

let lag_function =
  let rec power n x = if n <= 0 then 1 else x * power (n-1) x in
  power OpamSolverConfig.(!r.version_lag_power)

let opam2cudf_map universe version_map packages =
  let set_to_bool_map set =
    OpamPackage.Set.fold (fun nv -> OpamPackage.Map.add nv true)
      (packages %% set) OpamPackage.Map.empty
  in
  let base_map =
    OpamPackage.Set.fold (fun nv ->
        OpamPackage.Map.add nv
          { Cudf.default_package with
            Cudf.package = name_to_cudf nv.name;
            pkg_extra = [
              OpamCudf.s_source, `String(OpamPackage.name_to_string nv);
              OpamCudf.s_source_number, `String(OpamPackage.version_to_string nv);
            ];
          })
      packages OpamPackage.Map.empty
  in
  let only_packages m =
    OpamPackage.Map.merge
      (fun _ -> function None -> fun _ -> None | Some _ -> fun x -> x)
      base_map m
  in
  let installed_map = set_to_bool_map universe.u_installed in
  let reinstall_map = set_to_bool_map universe.u_reinstall in
  let installed_root_map = set_to_bool_map universe.u_installed_roots in
  let pinned_to_current_version_map = set_to_bool_map universe.u_pinned in
  let avoid_versions =
    match
      OpamStd.List.assoc_opt String.equal "avoid-version" universe.u_attrs
    with
    | None -> OpamPackage.Set.empty
    | Some attr -> Lazy.force attr
  in
  let version_lag_map =
    OpamPackage.Name.Map.fold (fun name version_set acc ->
        let nvers, vs =
          OpamPackage.Version.Set.fold (fun v (i,acc) ->
              if OpamPackage.Set.mem (OpamPackage.create name v) avoid_versions
              then i, acc
              else i+1, OpamPackage.Version.Map.add v i acc)
            version_set (0, OpamPackage.Version.Map.empty)
        in
        let nvers, vs =
          (* Place all avoid-versions after normal versions *)
          (* Not strictly necessary, but gives a better fallback in case the
             specific criteria for avoided versions are not set *)
          OpamPackage.Version.Set.fold (fun v (i,acc) ->
              if OpamPackage.Set.mem (OpamPackage.create name v) avoid_versions
              then i+1, OpamPackage.Version.Map.add v i acc
              else i, acc)
            version_set (nvers, vs)
        in
        OpamPackage.Version.Map.fold (fun v i ->
            let lag = lag_function (nvers - i - 1) in
            if lag > 0 then
              OpamPackage.Map.add (OpamPackage.create name v) lag
            else fun acc -> acc)
          vs acc)
      (OpamPackage.to_map packages)
      OpamPackage.Map.empty
  in
  let extras_maps =
    List.map (fun (label, set) ->
        let set = Lazy.force set in
        OpamPackage.Set.fold (fun nv ->
            OpamPackage.Map.add nv (label, `Int 1))
          (packages %% set) OpamPackage.Map.empty)
      universe.u_attrs
  in
  let add elts f map =
    OpamPackage.Map.merge (fun nv a b ->
        match a, b with
        | Some cp, None -> Some cp
        | Some cp, Some x -> Some (f nv x cp)
        | None, _ -> None)
      map elts
  in
  let univ0 =
    base_map
    |> add version_map (fun _ version cp -> {cp with Cudf.version})
    |> add installed_map (fun _ installed cp -> {cp with Cudf.installed})
    |> add reinstall_map (fun _ x cp ->
        {cp with Cudf.pkg_extra =
                   (OpamCudf.s_reinstall, `Bool x) :: cp.Cudf.pkg_extra})
    |> add installed_root_map (fun _ x cp ->
        {cp with Cudf.pkg_extra =
                   (OpamCudf.s_installed_root, `Bool x) :: cp.Cudf.pkg_extra})
    |> add pinned_to_current_version_map (fun _ x cp ->
        {cp with Cudf.pkg_extra =
                   (OpamCudf.s_pinned, `Bool x) :: cp.Cudf.pkg_extra})
    |> add version_lag_map (fun _ x cp ->
        {cp with Cudf.pkg_extra =
                   (OpamCudf.s_version_lag, `Int x) :: cp.Cudf.pkg_extra})
    |> List.fold_right (fun m ->
        add m (fun _ x cp -> {cp with Cudf.pkg_extra = x :: cp.Cudf.pkg_extra}))
      extras_maps
  in
  let preresolve_deps f =
    OpamFilter.atomise_extended f |>
    OpamFormula.map
      (fun (name, (filter, cstr)) ->
         let cstr = match cstr with
           | None -> None
           | Some (op, FString v) ->
             let v = OpamPackage.Version.of_string v in
             constraint_to_cudf version_map name (op, v)
           | _ -> assert false
         in
         Atom (name_to_cudf name, (filter, cstr))) |>
    OpamFormula.cnf_of_formula
  in
  let depends_map =
    OpamPackage.Map.map preresolve_deps
      (only_packages universe.u_depends)
  in
  let depends_map =
    let unav_dep =
      OpamFormula.Atom (OpamCudf.unavailable_package_name, (FBool true, None))
    in
    OpamPackage.Set.fold (fun nv ->
        OpamPackage.Map.update nv
          (fun deps -> OpamFormula.ands [unav_dep; deps])
          OpamFormula.Empty)
      (universe.u_installed -- Lazy.force universe.u_available)
      depends_map
  in
  let depopts_map =
    OpamPackage.Map.map preresolve_deps
      (only_packages universe.u_depopts)
  in
  let conflicts_map =
    OpamPackage.Map.mapi
      (fun nv conflicts ->
         (nv.name, None) ::
         (* prevents install of multiple versions of the same pkg *)
         OpamFormula.set_to_disjunction universe.u_packages conflicts)
      (only_packages universe.u_conflicts)
  in
  let conflicts_map_resolved =
    OpamPackage.Map.map (List.rev_map (atom2cudf universe version_map))
      conflicts_map
  in
  fun ~depopts ~build ~post ->
    let all_depends_map =
      if depopts then
        OpamPackage.Map.union (fun d dopts -> OpamFormula.(ands [d; dopts]))
          depends_map depopts_map
      else depends_map
    in
    let depends_map_resolved =
      OpamPackage.Map.map (fun f ->
          f
          |> OpamFormula.map (fun (name, (filter, cstr)) ->
              if OpamFilter.eval_to_bool ~default:false
                  (OpamFilter.deps_var_env ~build ~post) filter
              then Atom (name, cstr)
              else Empty)
          |> OpamFormula.ands_to_list
          |> List.map (OpamFormula.fold_right (fun acc x -> x::acc) []))
        all_depends_map
    in
    univ0
    |> add depends_map_resolved (fun _ depends cp -> {cp with Cudf.depends})
    |> add conflicts_map_resolved (fun _ conflicts cp -> {cp with Cudf.conflicts})

let opam2cudf_set universe version_map packages =
  let load_f = opam2cudf_map universe version_map packages in
  fun ~depopts ~build ~post ->
    OpamPackage.Map.fold (fun _ -> OpamCudf.Set.add)
      (load_f ~depopts ~build ~post)
      OpamCudf.Set.empty

let load_cudf_packages opam_universe ?version_map opam_packages =
  let chrono = OpamConsole.timer () in
  let version_map = match version_map with
    | Some vm -> vm
    | None -> cudf_versions_map opam_universe in
  log ~level:3 "Load cudf universe: opam2cudf";
  let univ_gen =
    opam2cudf_map opam_universe version_map opam_packages
  in
  log ~level:3 "Preload of cudf universe: done in %.3fs" (chrono ());
  fun ?(add_invariant=false) ?(depopts=false) ~build ~post () ->
    log "Load cudf universe (depopts:%a, build:%b, post:%b)"
      (slog string_of_bool) depopts
      build
      post;
    let chrono = OpamConsole.timer () in
    let cudf_packages_map = univ_gen ~depopts ~build ~post in
    log ~level:3 "opam2cudf: done in %.3fs" (chrono ());
    if add_invariant then
      let rec mk_key s =
        let k = OpamPackage.of_string (s^".~") in
        if OpamPackage.Map.mem k cudf_packages_map then mk_key (s ^ "-") else k
      in
      OpamPackage.Map.add (mk_key "opam-dummy-key.~")
        (opam_invariant_package version_map opam_universe.u_invariant)
        cudf_packages_map
    else
      cudf_packages_map

let map_to_cudf_universe cudf_packages_map =
  try Cudf.load_universe (OpamPackage.Map.values cudf_packages_map)
  with Cudf.Constraint_violation s ->
    OpamConsole.error_and_exit `Solver_failure
      "Malformed CUDF universe (%s)" s

(* load a cudf universe from an opam one *)
let load_cudf_universe opam_universe ?version_map opam_packages =
  let load_f = load_cudf_packages opam_universe ?version_map opam_packages in
  fun ?add_invariant ?depopts ~build ~post () ->
    log "Load cudf universe (depopts:%a, build:%b, post:%b)"
      (slog string_of_bool) OpamStd.Option.Op.(depopts +! false)
      build
      post;
    let chrono = OpamConsole.timer () in
    let cudf_packages_map = load_f ?add_invariant ?depopts ~build ~post () in
    let cudf_universe = map_to_cudf_universe cudf_packages_map in
    log ~level:3 "Secondary load of cudf universe: done in %.3fs" (chrono ());
    cudf_universe

let load_cudf_universe_with_packages
    opam_universe ?version_map all_packages
    ?add_invariant ?depopts ~build ~post
    opam_packages =
  let cudf_packages_map =
    load_cudf_packages opam_universe ?version_map all_packages
      ?add_invariant ?depopts ~build ~post ()
  in
  map_to_cudf_universe cudf_packages_map,
  OpamPackage.Set.fold
    (fun nv -> OpamCudf.Set.add (OpamPackage.Map.find nv cudf_packages_map))
    opam_packages
    OpamCudf.Set.empty

let string_of_request r =
  let to_string = OpamFormula.string_of_conjunction OpamFormula.string_of_atom in
  Printf.sprintf "install:%s remove:%s upgrade:%s"
    OpamFormula.(string_of_formula string_of_atom r.wish_install)
    (to_string r.wish_remove)
    (to_string r.wish_upgrade)

(* Unused?
let map_cause f = function
  | Upstream_changes -> Upstream_changes
  | Use l            -> Use (List.rev_map f l)
  | Required_by l    -> Required_by (List.rev_map f l)
  | Conflicts_with l -> Conflicts_with (List.rev_map f l)
  | Requested        -> Requested
  | Unknown          -> Unknown
*)

let cudf_to_opam_graph cudf2opam cudf_graph =
  let size = OpamCudf.ActionGraph.nb_vertex cudf_graph in
  let opam_graph = ActionGraph.create ~size () in
  OpamCudf.ActionGraph.iter_vertex (fun package ->
    ActionGraph.add_vertex opam_graph (map_action cudf2opam package)
  ) cudf_graph;
  OpamCudf.ActionGraph.iter_edges (fun p1 p2 ->
    ActionGraph.add_edge opam_graph
      (map_action cudf2opam p1)
      (map_action cudf2opam p2)
  ) cudf_graph;
  opam_graph

let map_request f r =
  let fl = List.rev_map f in
  { wish_install = OpamFormula.map (fun x -> Atom (f x))  r.wish_install;
    wish_remove  = fl r.wish_remove;
    wish_upgrade = fl r.wish_upgrade;
    wish_all = fl r.wish_all;
    criteria = r.criteria;
    extra_attributes = r.extra_attributes; }

let cycle_conflict ~version_map univ cycles =
  OpamCudf.cycle_conflict ~version_map univ cycles

let resolve universe request =
  log "resolve request=%a" (slog string_of_request) request;
  let all_packages = Lazy.force universe.u_available ++ universe.u_installed in
  let version_map = cudf_versions_map universe in
  let univ_gen = load_cudf_universe universe ~version_map all_packages in
  let cudf_universe = univ_gen ~depopts:false ~build:true ~post:true () in
  let requested_names =
    OpamPackage.Name.Set.of_list (List.map fst request.wish_all)
  in
  let request =
    let extra_attributes =
      OpamStd.List.sort_nodup compare
        (List.map fst universe.u_attrs @ request.extra_attributes)
    in
    { request with extra_attributes }
  in
  let request, deprequest_pkg =
    let conj = OpamFormula.ands_to_list request.wish_install in
    let conj, deprequest =
      List.partition (function Atom _ -> true | _ -> false) conj
    in
    {request with wish_install = OpamFormula.ands conj},
    opam_deprequest_package version_map (OpamFormula.ands deprequest)
  in
  let cudf_request = map_request (atom2cudf universe version_map) request in
  let invariant_pkg =
    opam_invariant_package version_map universe.u_invariant
  in
  let solution =
    try
      Cudf.add_package cudf_universe invariant_pkg;
      Cudf.add_package cudf_universe deprequest_pkg;
      let resp =
        OpamCudf.resolve ~extern:true ~version_map cudf_universe cudf_request
      in
      Cudf.remove_package cudf_universe OpamCudf.opam_deprequest_package;
      Cudf.remove_package cudf_universe OpamCudf.opam_invariant_package;
      OpamCudf.to_actions cudf_universe resp
    with OpamCudf.Solver_failure msg ->
      let bt = Printexc.get_raw_backtrace () in
      OpamConsole.error "%s" msg;
      Printexc.raise_with_backtrace
        OpamStd.Sys.(Exit (get_exit_code `Solver_failure))
        bt
  in
  match solution with
  | Conflicts _ as c -> c
  | Success actions ->
    let simple_universe = univ_gen ~depopts:true ~build:false ~post:false () in
    let complete_universe = univ_gen ~depopts:true ~build:true ~post:false () in
    try
      let atomic_actions =
        OpamCudf.atomic_actions
          ~simple_universe ~complete_universe actions in
      OpamCudf.trim_actions cudf_universe requested_names atomic_actions;
      Success atomic_actions
    with OpamCudf.Cyclic_actions cycles ->
      cycle_conflict ~version_map complete_universe cycles

let get_atomic_action_graph t =
  cudf_to_opam_graph OpamCudf.cudf2opam t

let dosetrim f =
  (* Dose_algo.Depsolver.trim => this can explode memory, we need to specify
     [~explain:false] *)
  let trimmed_pkgs = ref [] in
  let callback d =
    if Dose_algo.Diagnostic.is_solution d then
      match d.Dose_algo.Diagnostic.request with
      |[p] -> trimmed_pkgs := p::!trimmed_pkgs
      |_ -> assert false
  in
  ignore (f ~callback ~explain:false);
  !trimmed_pkgs

let coinstallable_subset universe ?(add_invariant=true) set packages =
  log "subset of coinstallable with %a within %a"
    (slog OpamPackage.Set.to_string) set
    (slog OpamPackage.Set.to_string) packages;
  let cudf_packages_map =
    load_cudf_packages ~add_invariant ~build:true ~post:true universe
      (Lazy.force universe.u_available ++ set ++ packages) ()
  in
  let cudf_set, cudf_packages_map =
    OpamPackage.Set.fold (fun nv (set, map) ->
        let p = OpamPackage.Map.find nv cudf_packages_map in
        let p = { p with Cudf.keep = `Keep_version; installed = true } in
        OpamCudf.Set.add p set, OpamPackage.Map.add nv p map)
      set (OpamCudf.Set.empty, cudf_packages_map)
  in
  let cudf_universe = map_to_cudf_universe cudf_packages_map in
  let cudf_set =
    if add_invariant then
      OpamCudf.Set.add
        (Cudf.lookup_package cudf_universe OpamCudf.opam_invariant_package)
        cudf_set
    else cudf_set
  in
  let cudf_universe = OpamCudf.trim_universe cudf_universe cudf_set in
  let cudf_packages =
    OpamPackage.Set.fold
      (fun nv acc ->
         let p = OpamPackage.Map.find nv cudf_packages_map in
         if Cudf.mem_package cudf_universe (p.Cudf.package, p.Cudf.version)
         then OpamPackage.Map.find nv cudf_packages_map :: acc
         else acc)
      packages
      []
  in
  let cudf_coinstallable =
    dosetrim (fun ~callback ~explain ->
        Dose_algo.Depsolver.listcheck ~callback ~explain
          cudf_universe cudf_packages)
  in
  List.fold_left (fun acc pkg ->
      if OpamCudf.is_opam_invariant pkg then acc
      else OpamPackage.Set.add (OpamCudf.cudf2opam pkg) acc)
    OpamPackage.Set.empty
    cudf_coinstallable

let installable_subset universe packages =
  coinstallable_subset
    universe ~add_invariant:true OpamPackage.Set.empty packages

let installable universe =
  installable_subset universe (Lazy.force universe.u_available)

module PkgGraph = Graph.Imperative.Digraph.ConcreteBidirectional(OpamPackage)

let dependency_graph
    ~depopts ~build ~post ~installed ~unavailable
    universe =
  let u_packages =
    if installed then universe.u_installed else
    if unavailable then universe.u_packages else
      Lazy.force universe.u_available in
  let cudf_graph =
    load_cudf_universe ~depopts ~build ~post universe u_packages () |>
    OpamCudf.Graph.of_universe
  in
  let g = PkgGraph.create ~size:(OpamCudf.Graph.nb_vertex cudf_graph) () in
  OpamCudf.Graph.iter_vertex (fun v ->
      PkgGraph.add_vertex g (OpamCudf.cudf2opam v))
    cudf_graph;
  OpamCudf.Graph.iter_edges (fun v1 v2 ->
      PkgGraph.add_edge g (OpamCudf.cudf2opam v1) (OpamCudf.cudf2opam v2))
    cudf_graph;
  g

let dependency_sort ~depopts ~build ~post universe packages =
  let cudf_universe, cudf_packages =
    load_cudf_universe_with_packages
      ~depopts ~build ~post universe universe.u_packages packages
  in
  List.map OpamCudf.cudf2opam
    (OpamCudf.dependency_sort cudf_universe cudf_packages)

let coinstallability_check universe packages =
  let version_map = cudf_versions_map universe in
  let cudf_universe, cudf_packages =
    load_cudf_universe_with_packages
      ~build:true ~post:true ~add_invariant:true
      universe ~version_map universe.u_packages packages
  in
  match
    Dose_algo.Depsolver.edos_coinstall cudf_universe
      (OpamCudf.Set.elements cudf_packages)
  with
  | { Dose_algo.Diagnostic.result = Dose_algo.Diagnostic.Success _; _ } ->
    None
  | { Dose_algo.Diagnostic.result = Dose_algo.Diagnostic.Failure _; _ } as c ->
    match OpamCudf.make_conflicts ~version_map cudf_universe c with
    | Conflicts cs -> Some cs
    | _ -> None

let check_for_conflicts universe =
  coinstallability_check universe universe.u_installed

let atom_coinstallability_check universe atoms =
  let version_map = cudf_versions_map universe in
  let check_pkg = {
    Cudf.default_package with
    package = "=check_coinstallability";
    depends = List.map (fun at -> [atom2cudf () version_map at]) atoms;
  } in
  let cudf_universe =
    Cudf.load_universe
      (check_pkg ::
       opam_invariant_package version_map universe.u_invariant ::
       OpamCudf.Set.elements
         (opam2cudf_set universe version_map (Lazy.force universe.u_available)
            ~depopts:false ~build:true ~post:true))
  in
  Dose_algo.Depsolver.edos_install cudf_universe check_pkg
  |> Dose_algo.Diagnostic.is_solution

let new_packages sol =
  OpamCudf.ActionGraph.fold_vertex (fun action packages ->
      match action with
      | `Install p | `Change (_,_,p) ->
        OpamPackage.Set.add (OpamCudf.cudf2opam p) packages
      | `Reinstall _ | `Remove _ | `Build _ | `Fetch _ -> packages
  ) sol OpamPackage.Set.empty

let removed_packages sol =
  OpamCudf.ActionGraph.fold_vertex (fun action packages ->
      match action with
      | `Remove p | `Change (_,p,_) ->
        OpamPackage.Set.add (OpamCudf.cudf2opam p) packages
      | `Install _ | `Reinstall _ | `Build _ | `Fetch _ -> packages
  ) sol OpamPackage.Set.empty

let all_packages sol =
  OpamCudf.ActionGraph.fold_vertex (fun action packages ->
      List.fold_left
        (fun packages p -> OpamPackage.Set.add (OpamCudf.cudf2opam p) packages)
        packages (full_action_contents action))
    sol OpamPackage.Set.empty

let stats sol =
  OpamCudf.ActionGraph.fold_vertex (fun action stats ->
      match action with
      | `Install _ -> {stats with s_install = stats.s_install+1}
      | `Change (`Up,_,_) -> {stats with s_upgrade = stats.s_upgrade+1}
      | `Change (`Down,_,_) -> {stats with s_downgrade = stats.s_downgrade+1}
      | `Reinstall _ -> {stats with s_reinstall = stats.s_reinstall+1}
      | `Remove _ -> {stats with s_remove = stats.s_remove+1}
      | `Build _ | `Fetch _ -> stats)
    (OpamCudf.ActionGraph.reduce sol)
    { s_install=0; s_reinstall=0; s_upgrade=0; s_downgrade=0; s_remove=0 }

let string_of_stats stats =
  let utf = (OpamConsole.utf8 ()) in
  let titles_stats = [
    `Remove (), stats.s_remove;
    `Change (`Down,(),()), stats.s_downgrade;
    `Reinstall (), stats.s_reinstall;
    `Change (`Up,(),()), stats.s_upgrade;
    `Install (), stats.s_install;
  ] in
  let titles_stats = List.filter (fun (_, n) -> n <> 0) titles_stats in
  let msgs =
    let open OpamActionGraph in
    List.map (fun (a, n) ->
        let noun =
          let sing, plur = noun_of_action a in
          if n = 1 then sing else plur
        in
        String.concat " "
          (if utf
           then [ action_color a (symbol_of_action a);
                  OpamConsole.colorise `bold (string_of_int n);
                  noun ]
           else [ OpamConsole.colorise `bold (string_of_int n);
                  action_color a noun ]))
      titles_stats
  in
  OpamStd.Format.pretty_list msgs

let solution_is_empty t =
  OpamCudf.ActionGraph.is_empty t

let print_solution ~messages ~append ~requested ~reinstall ~available
    ?(skip=OpamPackage.Map.empty) t =
  let dump_cudf sfx t = match OpamSolverConfig.(!r.cudf_file) with
    | None -> ()
    | Some f ->
      let filename = Printf.sprintf "%s-actions%s.dot" f sfx in
      let oc = open_out filename in
      ActionGraph.Dot.output_graph oc (cudf_to_opam_graph OpamCudf.cudf2opam t);
      close_out oc
  in
  dump_cudf "-full" t;
  let t = OpamCudf.ActionGraph.reduce t in
  dump_cudf "" t;
  let causes =
    OpamCudf.compute_root_causes t requested reinstall available
  in
  let actions, details =
    OpamCudf.ActionGraph.fold_vertex (fun a (actions,details) ->
        if OpamPackage.Map.mem OpamCudf.(cudf2opam (action_contents a)) skip
        then actions, details
        else
        let cause =
          try OpamCudf.Map.find (OpamCudf.action_contents a) causes
          with Not_found -> Unknown in
        let action = map_action OpamCudf.cudf2opam a in
        let cudf_name p =
          let nv = OpamCudf.cudf2opam p in
          let nv = try OpamPackage.Map.find nv skip with Not_found -> nv in
          OpamPackage.name_to_string nv
        in
        let cause = string_of_cause cudf_name cause in
        let messages =
          match a with
          | `Install p | `Change (_,_,p) | `Reinstall p ->
            messages (OpamCudf.cudf2opam p)
          | `Remove _ | `Build _ | `Fetch _ -> []
        in
        action :: actions, (cause, messages) :: details
      ) t ([],[])
  in
  let table =
    List.map2 (fun action (cause, messages) ->
        " " :: action @
        [if cause = "" then "" else Printf.sprintf "[%s]" cause] @
        if messages = [] then []
        else [String.concat "\n" messages]
      )
      (Action.to_aligned_strings ~append actions)
      details
    |> OpamStd.Format.align_table
  in
  let actions_table = List.combine actions table in
  let actions_table =
    List.sort (fun a1 a2 ->
        let ct (a, _) = OpamCudf.action_contents a in
        OpamPackage.compare (ct a1) (ct a2))
      actions_table
  in
  let print_actions filter =
    match List.filter (fun (a, _) -> filter a) actions_table with
    | [] -> ()
    | ((a,_) :: _) as acts ->
      OpamConsole.formatted_msg "%s %s %s %s\n"
        (OpamActionGraph.action_color a "===")
        (OpamActionGraph.name_of_action a)
        (OpamConsole.colorise `bold (string_of_int ((List.length acts))))
        (match acts with [_] -> "package" | _ -> "packages");
      OpamConsole.print_table ~sep:" " stdout (List.map snd acts)
  in
  print_actions (function `Remove _ -> true | _ -> false);
  print_actions (function `Change (`Down,_,_) -> true | _ -> false);
  print_actions (function `Reinstall _ -> true | _ -> false);
  print_actions (function `Change (`Up,_,_) -> true | _ -> false);
  print_actions (function `Install _ -> true | _ -> false)

let dump_universe universe oc =
  let version_map = cudf_versions_map universe in
  let cudf_univ =
    load_cudf_universe ~depopts:false ~build:true ~post:true ~version_map
      universe (Lazy.force universe.u_available) () in
  OpamCudf.dump_universe oc cudf_univ;
  (* Add explicit bindings to retrieve original versions of non-available and
     non-existing (but referred to) packages *)
  OpamPackage.Map.iter (fun nv i ->
      if not (OpamPackage.Set.mem nv (Lazy.force universe.u_available)) then
        Printf.fprintf oc "#v2v:%s:%d=%s\n"
          (OpamPackage.name_to_string nv) i (OpamPackage.version_to_string nv)
    ) version_map

let filter_solution ?(recursive=true) filter t =
  let t = OpamCudf.ActionGraph.copy t in
  let rec rm iter_deps v =
    if OpamCudf.ActionGraph.mem_vertex t v then (
      if recursive then iter_deps (rm iter_deps) t v;
      OpamCudf.ActionGraph.remove_vertex t v
    ) in
  OpamCudf.ActionGraph.iter_vertex
    (function
      | `Remove nv as a when not (filter (OpamCudf.cudf2opam nv)) ->
        rm OpamCudf.ActionGraph.iter_pred a
      | (`Install nv | `Change (_,_,nv)) as a
        when not (filter (OpamCudf.cudf2opam nv)) ->
        rm OpamCudf.ActionGraph.iter_succ a
      | _ -> ())
    t;
  t

let request ?(criteria=`Default)
    ?(install=[]) ?(upgrade=[]) ?(remove=[])
    ?(deprequest=OpamFormula.Empty)
    ?(all=install@upgrade@remove@
          OpamFormula.(atoms (of_atom_formula deprequest)))
    () =
  let wish_install, wish_upgrade =
    if OpamSolverConfig.best_effort () then
      deprequest, []
    else
      OpamFormula.ands (deprequest :: List.map (fun x -> Atom x) install), upgrade
  in
  { wish_install; wish_upgrade; wish_remove = remove; wish_all = all;
    criteria; extra_attributes = []; }
