// Abstract Syntax Tree (AST) definitions for Zig, closely following the grammar in zig-grammar.peg
package zig

// Root is the top-level node of a Zig source file.
type Root struct {
	ContainerDocComment DocComment // //! Doc Comment (optional)
	ContainerMembers    []*ContainerMember
}

type ContainerMember struct {
	DocComment DocComment // /// Doc Comment (optional)
	Comptime   bool       // 'comptime' field (optional)
	Field      *ContainerField
	Decl       Decl // Can be nil if this is a field
}

// ContainerField represents a field in a struct/enum/union container.
type ContainerField struct {
	Name      string // May be empty for anonymous fields
	Type      TypeExpr
	ByteAlign *Expr // Optional
	Value     Expr  // Optional initializer
}

// Decl is any top-level declaration (function, variable, usingnamespace, etc).
type Decl interface {
	isDecl()
}

// FnFlags is a bitfield for function declaration options.
type FnFlags uint8

const (
	FnExport FnFlags = 1 << iota
	FnExtern
	FnInline
	FnNoInline
	FnThreadLocal
)

// FnDecl represents a function declaration.
type FnDecl struct {
	Flags       FnFlags
	ExternName  string // Optional string for extern
	Name        string // May be empty (anonymous)
	Params      []*ParamDecl
	ByteAlign   *Expr
	AddrSpace   *Expr
	LinkSection *Expr
	CallConv    *Expr
	ReturnType  TypeExpr
	Body        *Block // nil means semicolon
}

func (*FnDecl) isDecl() {}

// GlobalVarFlags is a bitfield for global variable declaration options.
type GlobalVarFlags uint8

const (
	GlobalVarConst GlobalVarFlags = 1 << iota
	GlobalVarExport
	GlobalVarExtern
	GlobalVarThreadLocal
)

// GlobalVarDecl represents a top-level (global) variable or constant declaration.
// These are only allowed at the container/module scope and use a restricted syntax:
// no destructuring or multi-var declarations, just a single name and optional type/initializer.
type GlobalVarDecl struct {
	Flags       GlobalVarFlags
	ExternName  string // Optional string for extern
	Name        string
	Type        TypeExpr // Optional
	ByteAlign   *Expr
	AddrSpace   *Expr
	LinkSection *Expr
	Value       Expr // Optional initializer
}

func (*GlobalVarDecl) isDecl() {}

// UsingNamespaceDecl represents a 'usingnamespace' declaration.
type UsingNamespaceDecl struct {
	Expr Expr
}

func (*UsingNamespaceDecl) isDecl() {}

// ComptimeDecl represents a 'comptime' block at the container level.
type ComptimeDecl struct {
	Block *Block
}

func (*ComptimeDecl) isDecl() {}

// TestDecl represents a 'test' declaration.
type TestDecl struct {
	Name  string // Optional
	Block *Block
}

func (*TestDecl) isDecl() {}

// ParamDecl represents a function parameter.
type ParamDecl struct {
	DocComment DocComment // /// Doc Comment (optional)
	NoAlias    bool
	Comptime   bool
	Name       string   // May be empty
	Type       TypeExpr // 'anytype' if empty
}

// ContainerDecl represents a struct, enum, union, or opaque declaration.
type ContainerDecl struct {
	Extern     bool
	Packed     bool
	Kind       string   // "struct", "enum", "union", "opaque"
	TagType    TypeExpr // Optional (for enum/union)
	Fields     []*ContainerMember
	DocComment DocComment
}

func (*ContainerDecl) isDecl() {}

// ErrorSetDecl represents an error set declaration.
type ErrorSetDecl struct {
	Names []string
}

func (*ErrorSetDecl) isDecl() {}

// Block represents a block of statements.
type Block struct {
	Label string // Optional
	Stmts []Stmt
}

// Stmt is any statement.
type Stmt interface {
	isStmt()
}

// ExprStmt represents an expression statement (e.g. a function call as a statement).
type ExprStmt struct {
	Expr Expr
}

func (*ExprStmt) isStmt() {}

// VarDeclStmt represents a local variable or constant declaration statement inside a function or block.
// These support destructuring and multi-var declarations, and are only valid at statement/block scope.
type VarDeclStmt struct {
	Const       bool
	Pattern     VarPattern // Destructuring or multiple variable names
	Type        TypeExpr   // Optional
	Value       Expr       // Optional initializer
	ByteAlign   Expr       // Optional
	AddrSpace   Expr       // Optional
	LinkSection Expr       // Optional
}

func (*VarDeclStmt) isStmt() {}

// ReturnStmt represents a 'return' statement.
type ReturnStmt struct {
	Value Expr // Optional
}

func (*ReturnStmt) isStmt() {}

// IfStmt represents an if statement (with optional else branch and payload).
type IfStmt struct {
	Cond    Expr     // Condition expression
	Then    Stmt     // Then branch
	Else    Stmt     // Optional else branch
	Payload *Payload // Optional payload (for |x|, |*x|, |*x, y|, etc.)
}

func (*IfStmt) isStmt() {}

// IfExpr represents an if expression (with optional else branch and payload).
type IfExpr struct {
	Cond    Expr     // Condition expression
	Then    Expr     // Then branch
	Else    Expr     // Optional else branch
	Payload *Payload // Optional payload (for |x|, |*x|, |*x, y|, etc.)
}

// DeferStmt represents a 'defer' or 'errdefer' statement.
type DeferStmt struct {
	ErrDefer bool     // True for 'errdefer', false for 'defer'
	Payload  *Payload // Optional payload (for |x|, |*x|, etc.)
	Stmt     Stmt     // Statement to defer
}

func (*DeferStmt) isStmt() {}

// SuspendStmt represents a 'suspend' or 'nosuspend' statement.
type SuspendStmt struct {
	NoSuspend bool
	Stmt      Stmt
}

func (*SuspendStmt) isStmt() {}

// BlockStmt allows a block to be used as a statement.
type BlockStmt struct {
	Block *Block
}

func (*BlockStmt) isStmt() {}

// BreakStmt represents a 'break' statement.
type BreakStmt struct {
	Label string // Optional
	Value Expr   // Optional
}

func (*BreakStmt) isStmt() {}

// ContinueStmt represents a 'continue' statement.
type ContinueStmt struct {
	Label string // Optional
}

func (*ContinueStmt) isStmt() {}

// LoopStmt represents a for/while loop statement.
type LoopStmt struct {
	Inline  bool       // True if 'inline' is present
	Kind    string     // "for" or "while"
	Prefix  LoopPrefix // ForPrefix or WhilePrefix
	Body    Stmt       // Loop body
	Else    Stmt       // Optional else branch
	Payload *Payload   // Optional payload (for |x|, |*x|, |*x, y|, etc.)
}

func (*LoopStmt) isStmt() {}

// LoopPrefix is the prefix of a for/while loop.
type LoopPrefix interface{}

// ForPrefix represents the prefix of a for loop.
type ForPrefix struct {
	Args    []ForArg // For loop arguments
	Payload *Payload // Payload (|*x, y|, etc.)
}

// ForArg represents an argument in a for loop.
type ForArg struct {
	Expr Expr // Argument expression
	From Expr // Optional (for .. or ..<)
}

// WhilePrefix represents the prefix of a while loop.
type WhilePrefix struct {
	Cond     Expr     // Condition expression
	Payload  *Payload // Optional payload (for |x|, |*x|, etc.)
	Continue Expr     // Optional (while continue expression)
}

// SwitchStmt represents a switch statement.
type SwitchStmt struct {
	Cond   Expr
	Prongs []*SwitchProng
}

func (*SwitchStmt) isStmt() {}

// SwitchExpr represents a switch expression.
type SwitchExpr struct {
	Cond   Expr
	Prongs []*SwitchProng
}

// SwitchProng represents a prong in a switch.
type SwitchProng struct {
	Inline  bool          // True if 'inline' is present
	Cases   []*SwitchCase // List of cases for this prong
	Payload *Payload      // Optional payload (for |*x, y|, etc.)
	Expr    Expr          // Result expression for this prong
}

// SwitchCase represents a case in a switch.
type SwitchCase struct {
	Expr   Expr
	To     Expr // Optional (for ..)
	IsElse bool
}

// AsmExpr represents an inline assembly expression.
type AsmExpr struct {
	Volatile bool
	Template Expr
	Outputs  []*AsmOutputItem
	Inputs   []*AsmInputItem
	Clobbers []string
}

// AsmOutputItem represents an output operand in asm.
type AsmOutputItem struct {
	Name       string
	Constraint string
	Type       TypeExpr
}

// AsmInputItem represents an input operand in asm.
type AsmInputItem struct {
	Name       string
	Constraint string
	Expr       Expr
}

// InitListExpr represents an initializer list.
// Exactly one of Fields, Values, or Empty must be set (non-nil/non-empty or true).
type InitListExpr struct {
	Fields []*FieldInit // Field initializers (for {.foo = 1, .bar = 2}), mutually exclusive with Values/Empty
	Values []Expr       // Positional initializers (for {1, 2, 3}), mutually exclusive with Fields/Empty
	Empty  bool         // True if '{}', mutually exclusive with Fields/Values
}

// FieldInit represents a field initializer in an init list.
type FieldInit struct {
	Name  string
	Value Expr
}

// Identifier represents an identifier expression (variable, field, etc).
type Identifier struct {
	Name string // The identifier name
}

// Literal represents a literal value (int, float, string, char).
type Literal struct {
	Kind  string // "int", "float", "string", "char"
	Value string // The literal value as a string
}

// BinaryExpr represents a binary operation (e.g. +, -, *, /, etc).
type BinaryExpr struct {
	Op    string // Operator, e.g. "+", "-", "*", etc.
	Left  Expr   // Left operand
	Right Expr   // Right operand
}

// UnaryExpr represents a unary operation (e.g. !, -, ~, etc).
type UnaryExpr struct {
	Op   string // Operator, e.g. "-", "!", "~"
	Expr Expr   // Operand
}

// GroupedExpr represents a parenthesized expression.
type GroupedExpr struct {
	Expr Expr // The grouped expression
}

// CallExpr represents a function call.
type CallExpr struct {
	Fun  Expr   // Function being called
	Args []Expr // Arguments to the function
}

// FieldAccessExpr represents a field/member access as a suffix operation (e.g. foo.bar).
//
// Note: in order to call a function on an object, use a CallExpr with a Fun of a FieldAccessExpr.
// See TestHelloWorld for example.
type FieldAccessExpr struct {
	Receiver Expr   // The object being accessed
	Field    string // The field name
}

// IndexExpr represents an indexing operation as a suffix (e.g. arr[0]).
type IndexExpr struct {
	Receiver Expr // The object being indexed
	Index    Expr // The index expression
}

// ResumeExpr represents a 'resume' expression.
type ResumeExpr struct {
	Expr Expr // The expression to resume
}

// ComptimeExpr represents a 'comptime' expression.
type ComptimeExpr struct {
	Expr Expr // The expression to evaluate at comptime
}

// NosuspendExpr represents a 'nosuspend' expression.
type NosuspendExpr struct {
	Expr Expr // The expression to evaluate with nosuspend
}

// ContinueExpr represents a 'continue' expression.
type ContinueExpr struct {
	Label string // Optional label
}

// Expr is any expression.
type Expr interface{}

// TypeExpr is any type expression.
type TypeExpr interface{}

// PrefixTypeExpr represents a type with a string prefix. Examples include optionals and pointers.
type PrefixTypeExpr struct {
	Op   string
	Base TypeExpr
}

// ArrayTypeExpr represents an array type ([N]T).
type ArrayTypeExpr struct {
	Size Expr
	Elem TypeExpr
}

// SliceTypeExpr represents a slice type ([]T).
type SliceTypeExpr struct {
	Elem TypeExpr
}

// ErrorUnionTypeExpr represents an error union type (E!T).
type ErrorUnionTypeExpr struct {
	ErrSet TypeExpr
	Type   TypeExpr
}

// DocComment represents a doc comment (/// or //! lines).
// Newlines in the string automatically add more comments in the output.
type DocComment string

// Payload represents a control flow payload (|x|, |*x|, |*x, y|, etc).
// Each entry in Names corresponds to a variable name; the same index in Pointers is true if that name is a pointer (|*x|).
type Payload struct {
	Names    []string // Names in the payload, in order
	Pointers []bool   // True if the corresponding name is a pointer (|*x|, |*x, y|, |*x, *y|, etc.)
}

// LabeledBlock represents a labeled block or loop (label: {...}).
type LabeledBlock struct {
	Label string // The label name
	Block *Block // The labeled block
}

// LabeledTypeExpr represents a labeled type block (label: type).
type LabeledTypeExpr struct {
	Label string   // The label name
	Type  TypeExpr // The labeled type
}

// IfTypeExpr represents an if expression at the type level.
type IfTypeExpr struct {
	Cond    Expr
	Then    TypeExpr
	Else    TypeExpr // Optional
	Payload *Payload // Optional
}

// ForTypeExpr represents a for expression at the type level.
type ForTypeExpr struct {
	Prefix  *ForPrefix
	Body    TypeExpr
	Else    TypeExpr // Optional
	Payload *Payload // Optional
}

// WhileTypeExpr represents a while expression at the type level.
type WhileTypeExpr struct {
	Prefix  *WhilePrefix
	Body    TypeExpr
	Else    TypeExpr // Optional
	Payload *Payload // Optional
}

// DotAsteriskExpr represents a .*
type DotAsteriskExpr struct {
	Receiver Expr // The expression being dereferenced
}

// DotQuestionExpr represents a .?
type DotQuestionExpr struct {
	Receiver Expr // The expression being checked for optional
}

// AsyncExpr represents an 'async' expression.
type AsyncExpr struct {
	Expr Expr // The expression to be awaited asynchronously
}

// TryExpr represents a 'try' expression.
type TryExpr struct {
	Expr Expr // The expression to try
}

// AwaitExpr represents an 'await' expression.
type AwaitExpr struct {
	Expr Expr // The expression to await
}

// UnreachableExpr represents the 'unreachable' keyword.
type UnreachableExpr struct{}

// EmptyInitListExpr represents an empty initializer list '{}'.
type EmptyInitListExpr struct{}

// PositionalInitListExpr represents a positional initializer list '{expr, ...}'.
type PositionalInitListExpr struct {
	Values []Expr // Expressions in order
}

// FieldInitListExpr represents a field initializer list '{.field = expr, ...}'.
type FieldInitListExpr struct {
	Fields []*FieldInit // Field initializers
}

// SwitchProngPayload represents a switch prong payload (|*x, y|).
type SwitchProngPayload struct {
	Pointer bool
	Names   []string
}

// SwitchProngCase represents a single case in a switch prong.
type SwitchProngCase struct {
	Expr Expr // The case expression
	To   Expr // Optional, for ranges
}

// SwitchProngFull represents a full switch prong with cases and payload.
type SwitchProngFull struct {
	Inline  bool
	Cases   []*SwitchProngCase  // One or more cases
	Payload *SwitchProngPayload // Optional
	Expr    Expr                // The result expression
}

// SwitchElseProng represents an 'else' prong in a switch.
type SwitchElseProng struct {
	Expr Expr // The result expression
}

// VarPattern represents a variable pattern for destructuring or multiple variable declarations.
type VarPattern struct {
	Names []string // Variable names (single or multiple for destructuring)
}