// Package execenv manages isolated per-task execution environments for the daemon.
// Each task gets its own directory with injected context files. Repositories are
// checked out on demand by the agent via `multica repo checkout`.
package execenv

import (
	"encoding/json"
	"fmt"
	"log/slog"
	"os"
	"path/filepath"
	"time"
)

// RepoContextForEnv describes a workspace repo available for checkout.
type RepoContextForEnv struct {
	URL string // remote URL
}

// ProjectResourceForEnv describes a single resource attached to the issue's
// project. The resource_ref payload is type-specific JSON; the agent reads
// resources.json on disk for the full structure. This struct only carries
// fields the meta-skill template needs to render a human-readable summary
// (URL for github_repo, generic label otherwise).
type ProjectResourceForEnv struct {
	ID           string          // server-assigned UUID
	ResourceType string          // e.g. "github_repo"
	ResourceRef  json.RawMessage // raw JSONB payload from the API
	Label        string          // optional user-supplied label
}

// PrepareParams holds all inputs needed to set up an execution environment.
type PrepareParams struct {
	WorkspacesRoot string            // base path for all envs (e.g., ~/multica_workspaces)
	WorkspaceID    string            // workspace UUID — tasks are grouped under this
	TaskID         string            // task UUID — used for directory name
	AgentName      string            // for git branch naming only
	Provider       string            // agent provider (determines runtime config and skill injection paths)
	CodexVersion   string            // detected Codex CLI version (only used when Provider == "codex")
	OpenclawBin    string            // resolved openclaw CLI path (only used when Provider == "openclaw"); empty = look up on PATH
	Task           TaskContextForEnv // context data for writing files
}

// TaskContextForEnv is the subset of task context used for writing context files.
type TaskContextForEnv struct {
	IssueID                      string
	IssueTitle                   string
	IssueDescription             string
	TriggerCommentID             string // comment that triggered this task (empty for on_assign)
	TriggerCommentContent        string
	AgentID                      string // unique ID of the dispatched agent
	AgentName                    string
	AgentInstructions            string // agent identity/persona instructions, injected into CLAUDE.md
	AgentSkills                  []SkillContextForEnv
	Repos                        []RepoContextForEnv     // workspace repos available for checkout
	ProjectID                    string                  // issue's project, when present
	ProjectTitle                 string                  // human-readable project title
	ProjectResources             []ProjectResourceForEnv // resources attached to the project
	HasIssueOrCommentAttachments bool                    // true when the issue or any issue comment has attachments
	ChatSessionID                string                  // non-empty for chat tasks
	ChatMessage                  string
	ChatMessageAttachments       []AttachmentContextForEnv
	AutopilotRunID               string // non-empty for autopilot run_only tasks
	AutopilotID                  string
	AutopilotTitle               string
	AutopilotDescription         string
	AutopilotSource              string
	AutopilotTriggerPayload      string
	QuickCreatePrompt            string // non-empty for quick-create tasks
	IsSquadLeader                bool   // true when the agent is acting as a squad leader (may exit silently on no_action)
}

// AttachmentContextForEnv is the minimal attachment metadata needed for
// capability derivation. The agent fetches full metadata through the CLI.
type AttachmentContextForEnv struct {
	ID          string
	Filename    string
	ContentType string
}

// SkillContextForEnv represents a skill to be written into the execution environment.
type SkillContextForEnv struct {
	Name    string
	Content string
	Files   []SkillFileContextForEnv
}

// SkillFileContextForEnv represents a supporting file within a skill.
type SkillFileContextForEnv struct {
	Path    string
	Content string
}

// Environment represents a prepared, isolated execution environment.
type Environment struct {
	// RootDir is the top-level env directory ({workspacesRoot}/{task_id_short}/).
	RootDir string
	// WorkDir is the directory to pass as Cwd to the agent ({RootDir}/workdir/).
	WorkDir string
	// CodexHome is the path to the per-task CODEX_HOME directory (set only for codex provider).
	CodexHome string
	// OpenclawConfigPath is the path to the per-task synthesized OpenClaw
	// config (set only for openclaw provider). The daemon exports this as
	// OPENCLAW_CONFIG_PATH on the openclaw subprocess so its native skill
	// scanner pins workspaceDir to WorkDir.
	OpenclawConfigPath string
	// OpenclawIncludeRoot is the directory of the user's active OpenClaw
	// config (set only for openclaw provider with an on-disk user config).
	// The daemon must prepend it to OPENCLAW_INCLUDE_ROOTS so OpenClaw is
	// allowed to follow the wrapper's `$include` link out of envRoot into
	// the user's config — by default OpenClaw confines `$include` to the
	// directory holding the wrapper file. Empty when no $include is
	// emitted (fresh install).
	OpenclawIncludeRoot string

	logger *slog.Logger // for cleanup logging
}

// PredictRootDir returns the env root path that Prepare would create for the
// given task, without performing any I/O. Callers use this to claim ownership
// of the directory (e.g. against the GC loop) before Prepare/Reuse runs.
func PredictRootDir(workspacesRoot, workspaceID, taskID string) string {
	if workspacesRoot == "" || workspaceID == "" || taskID == "" {
		return ""
	}
	return filepath.Join(workspacesRoot, workspaceID, shortID(taskID))
}

// Prepare creates an isolated execution environment for a task.
// The workdir starts empty (no repo checkouts). The agent checks out repos
// on demand via `multica repo checkout <url>`.
func Prepare(params PrepareParams, logger *slog.Logger) (*Environment, error) {
	if params.WorkspacesRoot == "" {
		return nil, fmt.Errorf("execenv: workspaces root is required")
	}
	if params.WorkspaceID == "" {
		return nil, fmt.Errorf("execenv: workspace ID is required")
	}
	if params.TaskID == "" {
		return nil, fmt.Errorf("execenv: task ID is required")
	}

	envRoot := filepath.Join(params.WorkspacesRoot, params.WorkspaceID, shortID(params.TaskID))

	// Remove existing env if present (defensive — task IDs are unique).
	if _, err := os.Stat(envRoot); err == nil {
		if err := os.RemoveAll(envRoot); err != nil {
			return nil, fmt.Errorf("execenv: remove existing env: %w", err)
		}
	}

	// Create directory tree.
	workDir := filepath.Join(envRoot, "workdir")
	for _, dir := range []string{workDir, filepath.Join(envRoot, "output"), filepath.Join(envRoot, "logs")} {
		if err := os.MkdirAll(dir, 0o755); err != nil {
			return nil, fmt.Errorf("execenv: create directory %s: %w", dir, err)
		}
	}

	env := &Environment{
		RootDir: envRoot,
		WorkDir: workDir,
		logger:  logger,
	}

	// Write context files into workdir (skills go to provider-native paths).
	if err := writeContextFiles(workDir, params.Provider, params.Task); err != nil {
		return nil, fmt.Errorf("execenv: write context files: %w", err)
	}

	// For Codex, set up a per-task CODEX_HOME seeded from ~/.codex/ with skills.
	if params.Provider == "codex" {
		codexHome := filepath.Join(envRoot, "codex-home")
		if err := prepareCodexHomeWithOpts(codexHome, CodexHomeOptions{CodexVersion: params.CodexVersion}, logger); err != nil {
			return nil, fmt.Errorf("execenv: prepare codex-home: %w", err)
		}
		if err := hydrateCodexSkills(codexHome, params.Task.AgentSkills, logger); err != nil {
			return nil, fmt.Errorf("execenv: hydrate codex skills: %w", err)
		}
		env.CodexHome = codexHome
	}

	// For OpenClaw, synthesize a per-task config that pins workspace to
	// workDir. The skill scanner then reads {workDir}/skills/ (written by
	// writeContextFiles above). Fail closed on errors: a malformed user
	// config that the openclaw CLI can't read is a real problem and
	// silently degrading to a minimal config would mask it by booting
	// OpenClaw without the agents / providers / API keys it expects.
	if params.Provider == "openclaw" {
		result, err := prepareOpenclawConfig(envRoot, workDir, OpenclawConfigPrep{OpenclawBin: params.OpenclawBin})
		if err != nil {
			return nil, fmt.Errorf("execenv: prepare openclaw config: %w", err)
		}
		env.OpenclawConfigPath = result.ConfigPath
		env.OpenclawIncludeRoot = result.IncludeRoot
	}

	logger.Info("execenv: prepared env", "root", envRoot, "repos_available", len(params.Task.Repos))
	return env, nil
}

// ReuseParams describes the inputs to Reuse. It mirrors PrepareParams for
// the per-provider knobs (CodexVersion, OpenclawBin) so callers can pass
// the same resolved binary path on both first-run and reuse paths.
type ReuseParams struct {
	WorkDir      string
	Provider     string
	CodexVersion string            // only used when Provider == "codex"
	OpenclawBin  string            // only used when Provider == "openclaw"; empty = PATH lookup
	Task         TaskContextForEnv // refreshed context files / skills
}

// Reuse wraps an existing workdir into an Environment and refreshes context files.
// Returns nil if the workdir does not exist (caller should fall back to Prepare).
func Reuse(params ReuseParams, logger *slog.Logger) *Environment {
	if _, err := os.Stat(params.WorkDir); err != nil {
		return nil
	}

	env := &Environment{
		RootDir: filepath.Dir(params.WorkDir),
		WorkDir: params.WorkDir,
		logger:  logger,
	}

	// Refresh context files (issue_context.md, skills).
	if err := writeContextFiles(params.WorkDir, params.Provider, params.Task); err != nil {
		logger.Warn("execenv: refresh context files failed", "error", err)
	}

	// Restore CodexHome for Codex provider — the per-task codex-home directory
	// lives alongside the workdir. Re-run prepareCodexHomeWithOpts to ensure
	// config (especially sandbox/network access) is up to date.
	if params.Provider == "codex" {
		codexHome := filepath.Join(env.RootDir, "codex-home")
		if err := prepareCodexHomeWithOpts(codexHome, CodexHomeOptions{CodexVersion: params.CodexVersion}, logger); err != nil {
			logger.Warn("execenv: refresh codex-home failed", "error", err)
		} else {
			env.CodexHome = codexHome
			if err := hydrateCodexSkills(codexHome, params.Task.AgentSkills, logger); err != nil {
				logger.Warn("execenv: refresh codex skills failed", "error", err)
			}
		}
	}

	// Refresh the per-task OpenClaw config on reuse — the user may have
	// added/removed agents or rotated providers since the prior task ran,
	// and the workspace override always re-targets the current workDir.
	// Fail closed: a user config that can no longer be parsed should block
	// reuse rather than degrade to a minimal config that boots OpenClaw
	// without the registered agents.
	if params.Provider == "openclaw" {
		result, err := prepareOpenclawConfig(env.RootDir, params.WorkDir, OpenclawConfigPrep{OpenclawBin: params.OpenclawBin})
		if err != nil {
			logger.Warn("execenv: refresh openclaw config failed", "error", err)
			return nil
		}
		env.OpenclawConfigPath = result.ConfigPath
		env.OpenclawIncludeRoot = result.IncludeRoot
	}

	logger.Info("execenv: reusing env", "workdir", params.WorkDir)
	return env
}

// hydrateCodexSkills populates the per-task CODEX_HOME/skills directory with
// both user-installed skills (from the shared ~/.codex/skills/) and
// workspace-assigned skills. Workspace skills win on name conflict — they are
// written last and seedUserCodexSkills already pre-filters their names.
//
// The skills directory is wiped first so two stale-state classes that the
// Reuse path would otherwise leak are gone:
//
//   - A name now claimed by a workspace skill that previously held only a
//     user-seeded copy — support files from the user version would otherwise
//     linger under the workspace skill's directory.
//   - A user skill removed from the shared ~/.codex/skills/ since the last
//     run — its old contents would otherwise remain visible to the codex
//     CLI.
//
// Codex is the only runtime that needs this two-stage hydration because the
// daemon sets CODEX_HOME to a per-task directory, isolating the CLI from the
// user's real ~/.codex/. Other runtimes leave HOME untouched and discover
// user-level skills natively (see context.go for the workdir-local paths
// they use for workspace skills).
func hydrateCodexSkills(codexHome string, workspaceSkills []SkillContextForEnv, logger *slog.Logger) error {
	skillsDir := filepath.Join(codexHome, "skills")
	if err := os.RemoveAll(skillsDir); err != nil {
		return fmt.Errorf("clear codex skills dir: %w", err)
	}
	if err := seedUserCodexSkills(codexHome, workspaceSkills, logger); err != nil {
		logger.Warn("execenv: seed user codex skills failed", "error", err)
	}
	if len(workspaceSkills) == 0 {
		return nil
	}
	return writeSkillFiles(skillsDir, workspaceSkills)
}

// GCMetaKind identifies which kind of parent record a task workdir belongs to.
// The GC loop dispatches its decision tree on this value so chat / autopilot /
// quick-create tasks are no longer forced through the issue-centric path.
type GCMetaKind string

const (
	GCKindIssue        GCMetaKind = "issue"
	GCKindChat         GCMetaKind = "chat"
	GCKindAutopilotRun GCMetaKind = "autopilot_run"
	GCKindQuickCreate  GCMetaKind = "quick_create"
)

// GCMeta is persisted to .gc_meta.json inside the env root so the GC loop
// can decide whether the directory is reclaimable. It is a discriminated
// union keyed on Kind: only the ID field matching Kind is meaningful.
//
// Older meta files (pre-v2) lack the Kind field; readers must default empty
// Kind to GCKindIssue for backward compatibility — only IssueID was written
// before, and only issue-centric tasks ever produced a meta file.
type GCMeta struct {
	Kind           GCMetaKind `json:"kind,omitempty"`
	IssueID        string     `json:"issue_id,omitempty"`
	ChatSessionID  string     `json:"chat_session_id,omitempty"`
	AutopilotRunID string     `json:"autopilot_run_id,omitempty"`
	TaskID         string     `json:"task_id,omitempty"`
	WorkspaceID    string     `json:"workspace_id"`
	CompletedAt    time.Time  `json:"completed_at"`
}

const gcMetaFile = ".gc_meta.json"

// WriteGCMeta writes GC metadata into the given directory. The caller is
// responsible for choosing Kind and populating the matching ID field;
// CompletedAt is stamped here so callers don't have to think about clocks.
func WriteGCMeta(envRoot string, meta GCMeta, logger *slog.Logger) error {
	if envRoot == "" {
		return nil
	}
	if meta.Kind == "" {
		// Defensive: a task that doesn't fit any known kind would write a
		// meta file the GC loop can't dispatch on. Skip silently — the
		// directory falls back to the orphan-by-mtime path.
		logger.Debug("execenv: skipping .gc_meta.json write: kind is empty", "envRoot", envRoot)
		return nil
	}
	meta.CompletedAt = time.Now().UTC()
	data, err := json.Marshal(meta)
	if err != nil {
		return fmt.Errorf("marshal gc meta: %w", err)
	}
	return os.WriteFile(filepath.Join(envRoot, gcMetaFile), data, 0o644)
}

// ReadGCMeta reads GC metadata from a task directory root. Pre-v2 meta files
// (no kind field) are normalized to GCKindIssue so the legacy issue path
// keeps working without a migration.
func ReadGCMeta(envRoot string) (*GCMeta, error) {
	data, err := os.ReadFile(filepath.Join(envRoot, gcMetaFile))
	if err != nil {
		return nil, err
	}
	var meta GCMeta
	if err := json.Unmarshal(data, &meta); err != nil {
		return nil, err
	}
	if meta.Kind == "" {
		meta.Kind = GCKindIssue
	}
	return &meta, nil
}

// Cleanup tears down the execution environment.
// If removeAll is true, the entire env root is deleted. Otherwise, workdir is
// removed but output/ and logs/ are preserved for debugging.
func (env *Environment) Cleanup(removeAll bool) error {
	if env == nil {
		return nil
	}

	if removeAll {
		if err := os.RemoveAll(env.RootDir); err != nil {
			env.logger.Warn("execenv: cleanup removeAll failed", "error", err)
			return err
		}
		return nil
	}

	// Partial cleanup: remove workdir, keep output/ and logs/.
	if err := os.RemoveAll(env.WorkDir); err != nil {
		env.logger.Warn("execenv: cleanup workdir failed", "error", err)
		return err
	}
	return nil
}