// Package workflow implements a v3.x workflow orchestration engine (current baseline: v3.16)
// that supports multi-step output, API calls, structured output (v3.7+), output_config passthrough (v3.7+),
// schema reuse with schemaRef (v3.9+), unified LLM output semantics with _result/_meta/_error (v3.10+),
// stream as top-level LLM_* node attribute (v3.12+), run_events structured event stream (v3.12+),
// file_start/file_done run_events for file write lifecycle tracking (v3.13+),
// Download_*/Unzip_* nodes, .tmp/ path isolation, _iterDir, Write prepend (v3.14+),
// Pause_* nodes with resume protocol for explicit workflow suspension (v3.15+),
// Loop_* while-mode with maxIterations, BREAK keyword, and multi-provider LLM with model field (v3.16+).
package workflow

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"sync"
	"time"
)

// WorkflowType represents the type/location of a workflow
type WorkflowType string

const (
	WorkflowTypeIDE      WorkflowType = "IDE"      // IDE agent flow (Process/) - no Service_* nodes allowed
	WorkflowTypeBusiness WorkflowType = "Business" // Business workflow (Workflows/) - can call services
	WorkflowTypeApproval WorkflowType = "Approval" // Approval workflow (Workflows/) - can call services
	WorkflowTypeLocal    WorkflowType = "Local"    // Local workflow (LocalWorkflows/) - developer self-use
)

// Workflow represents the top-level workflow structure.
type Workflow struct {
	Version      string       `json:"version"`                // Current baseline: "3.13" (older v3.x versions remain compatibility-supported)
	Name         string       `json:"name"`                   // Workflow name
	Registry     Registry     `json:"registry"`               // External resources and global boundaries
	Steps        []Step       `json:"steps"`                  // Node list (workflow body)
	WorkflowType WorkflowType `json:"workflowType,omitempty"` // Optional: IDE, Business, Approval, Local
}

// Step represents a workflow step/node with common properties
type Step struct {
	ID         string            `json:"id"`                   // Unique identifier (with type prefix like Service_xxx, LLM_xxx)
	If         string            `json:"if,omitempty"`         // Execution condition expression
	In         StepInput         `json:"in,omitempty"`         // Input parameters
	Out        StepOutput        `json:"out,omitempty"`        // Output mapping to global vars and files
	Target     string            `json:"target,omitempty"`     // Write target (for Set_*, Write_*, Download_*)
	Value      string            `json:"value,omitempty"`      // Write value expression (for Set_*, Write_*)
	Source     interface{}       `json:"source,omitempty"`     // Data source: expression string (Loop_*), URL/object (Download_*), zip path (Unzip_*)
	RouteByExt map[string]string `json:"routeByExt,omitempty"` // v3.14+: extension→dir routing (Download_*, Unzip_*)
	DefaultDir string            `json:"defaultDir,omitempty"` // v3.14+: fallback dir when routeByExt has no match
	Overwrite  *bool             `json:"overwrite,omitempty"`  // v3.14+: overwrite flag for Unzip_* (default true)
	Children   []string          `json:"children,omitempty"`   // Parallel child branch entry points
	Next       string            `json:"next,omitempty"`       // Serial successor node
	OnError    string            `json:"onError,omitempty"`    // v3.10+: error handler step ID (jump here instead of failing)
	Cases      [][]string        `json:"cases,omitempty"`      // Conditional branches (for Branch_*) - [expression, stepId]
	Mode       string            `json:"mode,omitempty"`       // Execution mode (for Loop_*, Write_*)
	Print              string        `json:"print,omitempty"`              // v3.13+: expression emitted as step_print RunEvent after successful execution
	Reason             string        `json:"reason,omitempty"`             // v3.15+: Pause_* display reason for frontend/notifications
	ResumeResultTarget string        `json:"resumeResultTarget,omitempty"` // v3.15+: Pause_* target $vars path for resume payload (required for Pause_*)
	Timeout            *PauseTimeout `json:"timeout,omitempty"`            // v3.15+: Pause_* optional timeout configuration
	While              string        `json:"while,omitempty"`              // v3.16+: Loop_* while-expression (mutually exclusive with source)
	MaxIterations      *int          `json:"maxIterations,omitempty"`      // v3.16+: Loop_* iteration cap (required with while, optional with source)
	Model              string        `json:"model,omitempty"`              // v3.16+: LLM_* provider/model selector (e.g. "openai", "openai/gpt-4.1")
	Meta               Metadata      `json:"meta,omitempty"`               // Metadata for display/debugging
}

// RunParams carries run-level execution control parameters (v3.15+, spec §2.2).
// These are distinct from the workflow's registry.params (which are workflow
// design-time parameters); RunParams control how a particular execution is
// dispatched and scoped by the platform.
type RunParams struct {
	Params      map[string]interface{} `json:"params,omitempty"`      // Business input params (declared in registry.params, spec §1.7)
	WorkspaceID string                 `json:"workspaceId,omitempty"` // Workspace scope for this execution
	Nodes       []string               `json:"nodes,omitempty"`       // Subset of step IDs to selectively execute
	Mode        string                 `json:"mode,omitempty"`        // Execution mode: create / patch / regenerate / validate
}

// PauseTimeout configures the optional timeout for a Pause_* node (v3.15+).
type PauseTimeout struct {
	Sec int    `json:"sec"` // Timeout duration in seconds (must be > 0)
	On  string `json:"on"`  // Step ID to jump to on timeout (typically Stop_* or an error handler)
}

// DownloadSource represents the object form of a Download_* source field.
// When source is a string, it is treated as a plain URL.
type DownloadSource struct {
	URL      string            `json:"url"`               // Required: download URL
	Headers  map[string]string `json:"headers,omitempty"` // Optional: extra HTTP request headers
	Auth     string            `json:"auth,omitempty"`    // Optional: auth credential reference
	Timeout  int               `json:"timeout,omitempty"` // Optional: timeout in seconds
	Checksum string            `json:"checksum,omitempty"` // Optional: expected checksum (sha256:hex)
}

// StepInput represents the input parameters for a step
type StepInput map[string]interface{}

// StepOutput represents the output mapping from _result to global variables
type StepOutput map[string]string

// UnmarshalJSON supports both the full object form {"$var": "=_result"} and
// the string shorthand "$var" (equivalent to {"$var": "=_result"}).
func (s *StepOutput) UnmarshalJSON(data []byte) error {
	// Try object form first
	var m map[string]string
	if err := json.Unmarshal(data, &m); err == nil {
		*s = StepOutput(m)
		return nil
	}
	// Try string shorthand: "$var" → {"$var": "=_result"}
	var str string
	if err := json.Unmarshal(data, &str); err == nil {
		*s = StepOutput{str: "=_result"}
		return nil
	}
	return fmt.Errorf("out field must be a string or object, got: %s", string(data))
}

// Metadata contains display/debugging information
type Metadata map[string]interface{}

// ExecutionContext holds the runtime state during workflow execution
type ExecutionContext struct {
	Ctx              context.Context        // Go context for cancellation
	WorkflowID       string                 // Workflow execution instance ID
	Params           map[string]interface{} // Input parameters (read-only)
	ParamTypes       map[string]string      // Parameter type declarations from registry
	Variables        map[string]interface{} // Global variables ($vars)
	VarTypes         map[string]string      // Variable type declarations from registry
	SystemVars       map[string]interface{} // System variables (SYSVAR.xxx)
	LocalVars        map[string]interface{} // Local variables (_item, _index, _result)
	Artifacts        map[string]string      // Temporary file references
	CurrentStepID    string                 // Current executing step
	Status           ExecutionStatus        // Current execution status
	StartTime        time.Time              // Execution start time
	RunEventStream   chan RunEvent          // v3.12+: structured run_events stream (spec Chapter 13)
	ServiceAdapter   ServiceAdapter         // Adapter for calling services
	APIAdapter       APIAdapter             // Adapter for calling third-party APIs
	ComponentAdapter ComponentAdapter       // Adapter for calling components
	LLMAdapter         LLMAdapter             // Adapter for calling LLMs
	LLMAdapterRegistry *LLMAdapterRegistry    // v3.16+: multi-provider LLM adapter registry (nil for pre-3.16)
	FileAdapter        FileAdapter            // Adapter for file operations
	DocAdapter       DocAdapter             // Adapter for resolving semantic documents
	PauseState       *PauseState            // v3.15+: current pause state (non-nil only when Status == StatusPaused)
	pauseMu          sync.Mutex             // v3.15+: protects PauseState pointer field
	RunParams        *RunParams             // v3.15+: optional run-level control parameters (spec §2.2)
}

// ExecutionStatus represents the current status of workflow execution
type ExecutionStatus string

const (
	StatusRunning   ExecutionStatus = "running"
	StatusCompleted ExecutionStatus = "completed"
	StatusFailed    ExecutionStatus = "failed"
	StatusStopped   ExecutionStatus = "stopped"
	StatusPaused    ExecutionStatus = "paused" // v3.15+: workflow is suspended at a Pause_* node, awaiting resume
)

// RunEventType represents the type of a run_events event (spec 3.12 Chapter 13)
type RunEventType string

const (
	RunEventWorkflowStart     RunEventType = "workflow_start"
	RunEventWorkflowDone      RunEventType = "workflow_done"
	RunEventWorkflowFailed    RunEventType = "workflow_failed"
	RunEventWorkflowCancelled RunEventType = "workflow_cancelled"
	RunEventStepStart         RunEventType = "step_start"
	RunEventStepDone          RunEventType = "step_done"
	RunEventStepError         RunEventType = "step_error"
	RunEventStepSkipped       RunEventType = "step_skipped"
	RunEventLLMToken          RunEventType = "llm_token"
	RunEventLLMDone           RunEventType = "llm_done"
	RunEventFileStart         RunEventType = "file_start"
	RunEventFileDone          RunEventType = "file_done"
	RunEventStepPrint         RunEventType = "step_print"
	RunEventPauseStart        RunEventType = "pause_start"    // v3.15+: workflow entered paused state at Pause_* node
	RunEventPauseResumed      RunEventType = "pause_resumed"  // v3.15+: resume succeeded, payload written, execution continuing
	RunEventPauseTimeout      RunEventType = "pause_timeout"  // v3.15+: pause timed out, jumping to timeout.on
	RunEventPauseRejected     RunEventType = "pause_rejected" // v3.15+: resume request rejected (invalid token, wrong state, etc.)
)

// RunEvent is a structured event emitted to the run_events stream (spec 3.12 Chapter 13).
// Each event is independently parseable and carries a monotonic sequence number.
type RunEvent struct {
	RunID   string                 `json:"run_id"`            // Workflow run instance ID
	Seq     uint64                 `json:"seq"`               // Monotonically increasing sequence number (from 1)
	Ts      string                 `json:"ts"`                // ISO 8601 timestamp, millisecond precision
	Type    RunEventType           `json:"type"`              // Event type (see RunEventType constants)
	StepID  *string                `json:"step_id"`           // Step ID, or null for workflow-level events
	Payload map[string]interface{} `json:"payload"`           // Event-specific payload (see spec 13.4)
}

// ServiceResult represents the result from a service call
type ServiceResult struct {
	Data map[string]interface{} `json:"data"` // Business result
}

// StepType represents the type of workflow step
type StepType string

const (
	StepTypeService   StepType = "Service"
	StepTypeAPI       StepType = "API"
	StepTypeComponent StepType = "Component"
	StepTypeLLM       StepType = "LLM"
	StepTypeSet       StepType = "Set"
	StepTypeWrite     StepType = "Write"
	StepTypeDownload  StepType = "Download" // v3.14+: stream-download a file from an external URL
	StepTypeUnzip     StepType = "Unzip"    // v3.14+: extract a zip archive and route entries by extension
	StepTypePause     StepType = "Pause"    // v3.15+: suspend workflow execution pending external resume
	StepTypeBranch    StepType = "Branch"
	StepTypeLoop      StepType = "Loop"
	StepTypeStop      StepType = "Stop"
	StepTypeNoop      StepType = "Noop" // Does nothing, useful for grouping children
)

// WriteMode represents the file write strategy
type WriteMode string

const (
	WriteModeOverwrite    WriteMode = "overwrite"
	WriteModeFailIfExists WriteMode = "failIfExists"
	WriteModeAppend       WriteMode = "append"
	WriteModePrepend      WriteMode = "prepend" // v3.14+: prepend content to the beginning of the file
)

// LoopMode represents the loop execution strategy
type LoopMode string

const (
	LoopModeParallel LoopMode = "parallel"
	LoopModeSerial   LoopMode = "serial"
)

// GetSystemVar retrieves a system variable by name
func (ctx *ExecutionContext) GetSystemVar(name string) (interface{}, bool) {
	val, ok := ctx.SystemVars[name]
	return val, ok
}

// SetSystemVar sets a system variable by name
func (ctx *ExecutionContext) SetSystemVar(name string, value interface{}) {
	if ctx.SystemVars == nil {
		ctx.SystemVars = make(map[string]interface{})
	}
	ctx.SystemVars[name] = value
}

// GetParam retrieves a parameter (non-thread-safe, for backward compatibility)
func (ctx *ExecutionContext) GetParam(key string) (interface{}, bool) {
	val, ok := ctx.Params[key]
	return val, ok
}

// GetVariable retrieves a global variable (non-thread-safe, for backward compatibility)
func (ctx *ExecutionContext) GetVariable(key string) (interface{}, bool) {
	val, ok := ctx.Variables[key]
	return val, ok
}

// SetVariable sets a global variable (non-thread-safe, for backward compatibility)
func (ctx *ExecutionContext) SetVariable(key string, value interface{}) {
	if ctx.Variables == nil {
		ctx.Variables = make(map[string]interface{})
	}
	ctx.Variables[key] = value
}

// GetLocalVar retrieves a local variable (non-thread-safe, for backward compatibility)
func (ctx *ExecutionContext) GetLocalVar(key string) (interface{}, bool) {
	val, ok := ctx.LocalVars[key]
	return val, ok
}

// SetLocalVar sets a local variable (non-thread-safe, for backward compatibility)
func (ctx *ExecutionContext) SetLocalVar(key string, value interface{}) {
	if ctx.LocalVars == nil {
		ctx.LocalVars = make(map[string]interface{})
	}
	ctx.LocalVars[key] = value
}

// DeleteLocalVar deletes a local variable (non-thread-safe, for backward compatibility)
func (ctx *ExecutionContext) DeleteLocalVar(key string) {
	delete(ctx.LocalVars, key)
}

// GetArtifact retrieves an artifact (non-thread-safe, for backward compatibility)
func (ctx *ExecutionContext) GetArtifact(key string) (string, bool) {
	val, ok := ctx.Artifacts[key]
	return val, ok
}

// SetArtifact sets an artifact (non-thread-safe, for backward compatibility)
func (ctx *ExecutionContext) SetArtifact(key string, value string) {
	if ctx.Artifacts == nil {
		ctx.Artifacts = make(map[string]string)
	}
	ctx.Artifacts[key] = value
}

// SetArrayIndex sets an array index (non-thread-safe, for backward compatibility)
func (ctx *ExecutionContext) SetArrayIndex(key string, index int, value interface{}) {
	root, ok := ctx.Variables[key]
	if !ok {
		slice := make([]interface{}, index+1)
		slice[index] = value
		ctx.Variables[key] = slice
		return
	}

	slice, ok := root.([]interface{})
	if !ok {
		slice = make([]interface{}, index+1)
		slice[index] = value
		ctx.Variables[key] = slice
		return
	}

	for len(slice) <= index {
		slice = append(slice, nil)
	}
	slice[index] = value
	ctx.Variables[key] = slice
}

// GetBaseContext returns itself for ExecutionContext
func (ctx *ExecutionContext) GetBaseContext() *ExecutionContext {
	return ctx
}

// SetCurrentStepID sets the current step ID (non-thread-safe)
func (ctx *ExecutionContext) SetCurrentStepID(stepID string) {
	ctx.CurrentStepID = stepID
}

// SetStatus sets the execution status (non-thread-safe)
func (ctx *ExecutionContext) SetStatus(status ExecutionStatus) {
	ctx.Status = status
}

// IsStopped returns true if the execution status is stopped
func (ctx *ExecutionContext) IsStopped() bool {
	return ctx.Status == StatusStopped
}

// SafeExecutionContext wraps ExecutionContext with thread-safe access
type SafeExecutionContext struct {
	*ExecutionContext
	varMutex      sync.RWMutex // Protects Variables map
	localMutex    sync.Mutex   // Protects LocalVars map
	artifactMutex sync.Mutex   // Protects Artifacts map
	sysMutex      sync.RWMutex // Protects SystemVars map
	statusMutex   sync.Mutex   // Protects Status, CurrentStepID
}

// NewSafeExecutionContext creates a thread-safe wrapper around ExecutionContext
func NewSafeExecutionContext(ctx *ExecutionContext) *SafeExecutionContext {
	return &SafeExecutionContext{
		ExecutionContext: ctx,
	}
}

// SwapLocalVars temporarily swaps LocalVars with proper locking
// Returns a cleanup function that must be called to restore original LocalVars
func (s *SafeExecutionContext) SwapLocalVars(newLocalVars map[string]interface{}) func() {
	s.localMutex.Lock()
	oldLocalVars := s.LocalVars
	s.LocalVars = newLocalVars
	s.localMutex.Unlock()

	// Return cleanup function
	return func() {
		s.localMutex.Lock()
		s.LocalVars = oldLocalVars
		s.localMutex.Unlock()
	}
}

// GetParam retrieves a parameter with read lock
func (s *SafeExecutionContext) GetParam(key string) (interface{}, bool) {
	s.varMutex.RLock()
	defer s.varMutex.RUnlock()
	val, ok := s.Params[key]
	return val, ok
}

// GetVariable retrieves a global variable with read lock
func (s *SafeExecutionContext) GetVariable(key string) (interface{}, bool) {
	s.varMutex.RLock()
	defer s.varMutex.RUnlock()
	val, ok := s.Variables[key]
	return val, ok
}

// SetVariable sets a global variable with write lock
func (s *SafeExecutionContext) SetVariable(key string, value interface{}) {
	s.varMutex.Lock()
	defer s.varMutex.Unlock()
	if s.Variables == nil {
		s.Variables = make(map[string]interface{})
	}
	s.Variables[key] = value
}

// GetLocalVar retrieves a local variable with lock
func (s *SafeExecutionContext) GetLocalVar(key string) (interface{}, bool) {
	s.localMutex.Lock()
	defer s.localMutex.Unlock()
	val, ok := s.LocalVars[key]
	return val, ok
}

// SetLocalVar sets a local variable with lock
func (s *SafeExecutionContext) SetLocalVar(key string, value interface{}) {
	s.localMutex.Lock()
	defer s.localMutex.Unlock()
	if s.LocalVars == nil {
		s.LocalVars = make(map[string]interface{})
	}
	s.LocalVars[key] = value
}

// DeleteLocalVar deletes a local variable with lock
func (s *SafeExecutionContext) DeleteLocalVar(key string) {
	s.localMutex.Lock()
	defer s.localMutex.Unlock()
	delete(s.LocalVars, key)
}

// GetArtifact retrieves an artifact reference with lock
func (s *SafeExecutionContext) GetArtifact(key string) (string, bool) {
	s.artifactMutex.Lock()
	defer s.artifactMutex.Unlock()
	val, ok := s.Artifacts[key]
	return val, ok
}

// SetArtifact sets an artifact reference with lock
func (s *SafeExecutionContext) SetArtifact(key string, value string) {
	s.artifactMutex.Lock()
	defer s.artifactMutex.Unlock()
	if s.Artifacts == nil {
		s.Artifacts = make(map[string]string)
	}
	s.Artifacts[key] = value
}

// GetStatus retrieves the execution status with lock
func (s *SafeExecutionContext) GetStatus() ExecutionStatus {
	s.statusMutex.Lock()
	defer s.statusMutex.Unlock()
	return s.Status
}

// SetStatus sets the execution status with lock
func (s *SafeExecutionContext) SetStatus(status ExecutionStatus) {
	s.statusMutex.Lock()
	defer s.statusMutex.Unlock()
	s.Status = status
}

// IsStopped returns true if the execution status is stopped (thread-safe)
func (s *SafeExecutionContext) IsStopped() bool {
	s.statusMutex.Lock()
	defer s.statusMutex.Unlock()
	return s.Status == StatusStopped
}

// GetCurrentStepID retrieves the current step ID with lock
func (s *SafeExecutionContext) GetCurrentStepID() string {
	s.statusMutex.Lock()
	defer s.statusMutex.Unlock()
	return s.CurrentStepID
}

// SetCurrentStepID sets the current step ID with lock
func (s *SafeExecutionContext) SetCurrentStepID(id string) {
	s.statusMutex.Lock()
	defer s.statusMutex.Unlock()
	s.CurrentStepID = id
}

// GetSystemVar retrieves a system variable with read lock
func (s *SafeExecutionContext) GetSystemVar(name string) (interface{}, bool) {
	s.sysMutex.RLock()
	defer s.sysMutex.RUnlock()
	val, ok := s.SystemVars[name]
	return val, ok
}

// SetSystemVar sets a system variable with write lock
func (s *SafeExecutionContext) SetSystemVar(name string, value interface{}) {
	s.sysMutex.Lock()
	defer s.sysMutex.Unlock()
	if s.SystemVars == nil {
		s.SystemVars = make(map[string]interface{})
	}
	s.SystemVars[name] = value
}

// SetArrayIndex atomically sets an array index with auto-grow
func (s *SafeExecutionContext) SetArrayIndex(key string, index int, value interface{}) {
	s.varMutex.Lock()
	defer s.varMutex.Unlock()

	root, ok := s.Variables[key]
	if !ok {
		// Create new array
		slice := make([]interface{}, index+1)
		slice[index] = value
		s.Variables[key] = slice
		return
	}

	slice, ok := root.([]interface{})
	if !ok {
		// Not an array, create new array
		slice = make([]interface{}, index+1)
		slice[index] = value
		s.Variables[key] = slice
		return
	}

	// Grow slice if necessary
	for len(slice) <= index {
		slice = append(slice, nil)
	}
	slice[index] = value
	s.Variables[key] = slice
}

// GetBaseContext returns the underlying ExecutionContext
func (s *SafeExecutionContext) GetBaseContext() *ExecutionContext {
	return s.ExecutionContext
}

// ChildExecutionContext provides isolated local variables for parallel branches
type ChildExecutionContext struct {
	Parent       *SafeExecutionContext
	LocalVars    map[string]interface{} // Isolated local scope
	localStopped bool                   // true after this branch hits Stop_*
}

// NewChildExecutionContext creates a child context with isolated local variables
func NewChildExecutionContext(parent *SafeExecutionContext) *ChildExecutionContext {
	return &ChildExecutionContext{
		Parent:    parent,
		LocalVars: make(map[string]interface{}),
	}
}

// GetParam delegates to parent (shared params)
func (c *ChildExecutionContext) GetParam(key string) (interface{}, bool) {
	return c.Parent.GetParam(key)
}

// GetVariable delegates to parent (shared globals)
func (c *ChildExecutionContext) GetVariable(key string) (interface{}, bool) {
	return c.Parent.GetVariable(key)
}

// SetVariable delegates to parent (shared globals)
func (c *ChildExecutionContext) SetVariable(key string, value interface{}) {
	c.Parent.SetVariable(key, value)
}

// GetLocalVar uses isolated local scope (no locking needed, single goroutine)
func (c *ChildExecutionContext) GetLocalVar(key string) (interface{}, bool) {
	val, ok := c.LocalVars[key]
	return val, ok
}

// SetLocalVar uses isolated local scope (no locking needed, single goroutine)
func (c *ChildExecutionContext) SetLocalVar(key string, value interface{}) {
	c.LocalVars[key] = value
}

// DeleteLocalVar deletes from isolated local scope
func (c *ChildExecutionContext) DeleteLocalVar(key string) {
	delete(c.LocalVars, key)
}

// GetArtifact delegates to parent (shared artifacts)
func (c *ChildExecutionContext) GetArtifact(key string) (string, bool) {
	return c.Parent.GetArtifact(key)
}

// SetArtifact delegates to parent (shared artifacts)
func (c *ChildExecutionContext) SetArtifact(key string, value string) {
	c.Parent.SetArtifact(key, value)
}

// GetSystemVar delegates to parent (shared system vars)
func (c *ChildExecutionContext) GetSystemVar(name string) (interface{}, bool) {
	return c.Parent.GetSystemVar(name)
}

// SetSystemVar delegates to parent (shared system vars)
func (c *ChildExecutionContext) SetSystemVar(name string, value interface{}) {
	c.Parent.SetSystemVar(name, value)
}

// SetArrayIndex delegates to parent (shared global arrays)
func (c *ChildExecutionContext) SetArrayIndex(key string, index int, value interface{}) {
	c.Parent.SetArrayIndex(key, index, value)
}

// GetBaseContext returns the parent's underlying ExecutionContext
func (c *ChildExecutionContext) GetBaseContext() *ExecutionContext {
	return c.Parent.ExecutionContext
}

// SetCurrentStepID delegates to parent (thread-safe)
func (c *ChildExecutionContext) SetCurrentStepID(stepID string) {
	c.Parent.SetCurrentStepID(stepID)
}

// SetStatus delegates to parent (thread-safe) and tracks local stopped flag
func (c *ChildExecutionContext) SetStatus(status ExecutionStatus) {
	if status == StatusStopped {
		c.localStopped = true
	}
	c.Parent.SetStatus(status)
}

// IsStopped returns true if THIS branch hit Stop_* (not sibling branches)
func (c *ChildExecutionContext) IsStopped() bool {
	return c.localStopped
}

// ContextAccessor provides an interface for accessing execution context
type ContextAccessor interface {
	GetParam(key string) (interface{}, bool)
	GetVariable(key string) (interface{}, bool)
	SetVariable(key string, value interface{})
	SetArrayIndex(key string, index int, value interface{})
	GetLocalVar(key string) (interface{}, bool)
	SetLocalVar(key string, value interface{})
	DeleteLocalVar(key string)
	GetArtifact(key string) (string, bool)
	SetArtifact(key string, value string)
	GetSystemVar(name string) (interface{}, bool)
	SetSystemVar(name string, value interface{})
	GetBaseContext() *ExecutionContext

	// Thread-safe status field access
	SetCurrentStepID(stepID string)
	SetStatus(status ExecutionStatus)
	IsStopped() bool // Branch-aware stopped check (child contexts check local flag, not global)
}

// resumeSignal carries the payload and request ID sent by a Resume call to unblock executePauseStep.
type resumeSignal struct {
	Payload   interface{} // The payload provided by the caller; written to resumeResultTarget
	RequestID string      // Caller-supplied idempotency key
}

// PauseState holds the runtime state of an active Pause_* node (v3.15+).
// It is created by executePauseStep and stored in ExecutionContext.PauseState
// for the duration of the pause. The Resume method uses it to send a signal.
type PauseState struct {
	mu             sync.Mutex         // protects all fields below
	ch             chan resumeSignal   // buffered(1): executePauseStep reads; Resume writes
	token          string             // expected token for resume validation
	nodeID         string             // Pause_* step ID (for pause_rejected events)
	seenRequestIDs map[string]bool    // idempotency: request IDs already processed
	resumed        bool               // true once a valid resume signal has been sent
}

// WaitToken returns the SHA-256 hex token that was published in the pause_start event.
// This is safe to call from any goroutine while the workflow is in StatusPaused.
func (p *PauseState) WaitToken() string {
	p.mu.Lock()
	defer p.mu.Unlock()
	return p.token
}

// ResumeRequest carries the caller-supplied fields for the Resume method (v3.15+).
// Field names correspond to the protocol-level resume request body defined in spec §11.4.1.
type ResumeRequest struct {
	RunID     string      // Optional: workflow run ID for explicit validation (spec §11.4.1 "runId"); if non-empty, must match execCtx.WorkflowID
	Token     string      // Must match the wait token from the pause_start event
	Payload   interface{} // Arbitrary data written to resumeResultTarget in $vars
	RequestID string      // Optional idempotency key; duplicate RequestIDs are silently no-ops
}

// ErrBreak is a sentinel error returned when a step's next is "BREAK".
// The enclosing Loop_* executor catches this to exit the loop immediately.
// It must never propagate past the loop handler.
var ErrBreak = errors.New("BREAK")

// IsBreakError checks if an error is the BREAK sentinel.
func IsBreakError(err error) bool {
	return errors.Is(err, ErrBreak)
}

// LLMError represents a structured LLM call failure (v3.10+)
type LLMError struct {
	Type             string                 // e.g., "rate_limit", "auth_error", "timeout"
	Code             string                 // e.g., "RATE_LIMIT"
	Message          string                 // Human-readable error message
	Retryable        bool                   // Whether the call can be retried
	StatusCode       int                    // HTTP status code
	Provider         string                 // LLM provider name
	Model            string                 // Model used
	RequestID        string                 // Request ID from provider
	ProviderError string                 // provider exception class
	Details          map[string]interface{} // Additional details
	Raw              map[string]interface{} // Raw error response
}

// Error implements the error interface
func (e *LLMError) Error() string {
	return fmt.Sprintf("%s: %s (code=%s, status=%d)", e.Type, e.Message, e.Code, e.StatusCode)
}

// ToMap converts LLMError to a map for use as _error local variable
func (e *LLMError) ToMap() map[string]interface{} {
	m := map[string]interface{}{
		"type":      e.Type,
		"code":      e.Code,
		"message":   e.Message,
		"retryable": e.Retryable,
	}
	if e.StatusCode != 0 {
		m["status_code"] = e.StatusCode
	}
	if e.Provider != "" {
		m["provider"] = e.Provider
	}
	if e.Model != "" {
		m["model"] = e.Model
	}
	if e.RequestID != "" {
		m["request_id"] = e.RequestID
	}
	if e.ProviderError != "" {
		m["provider_error"] = e.ProviderError
	}
	if e.Details != nil {
		m["details"] = e.Details
	}
	if e.Raw != nil {
		m["raw"] = e.Raw
	}
	return m
}