// Copyright 2026 Alibaba Group
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package pipeline

import (
	"fmt"
	"sort"
	"strings"
)

// Phase represents a named stage in the CLI execution pipeline.
// Handlers are grouped by phase and executed in chain order within
// each phase. Phases themselves execute in a fixed order defined
// by the engine.
type Phase int

const (
	// Register runs at CLI startup when the Cobra command tree is
	// being built. Handlers can add, remove, or modify commands.
	Register Phase = iota

	// PreParse runs before Cobra parses the raw argv. Handlers
	// receive the raw argument slice and can rewrite it — for
	// example to fix flag-name typos or split glued values.
	PreParse

	// PostParse runs after Cobra has successfully parsed flags and
	// args. Handlers receive structured parameters plus the tool
	// schema, enabling value-level corrections such as date format
	// normalisation.
	PostParse

	// PreRequest runs after validation, just before the JSON-RPC
	// call is dispatched. Handlers can inspect or mutate the final
	// payload.
	PreRequest

	// PostResponse runs after the transport returns a result and
	// before the output is written to stdout.
	PostResponse
)

// String returns the human-readable name of the phase.
func (p Phase) String() string {
	switch p {
	case Register:
		return "register"
	case PreParse:
		return "pre-parse"
	case PostParse:
		return "post-parse"
	case PreRequest:
		return "pre-request"
	case PostResponse:
		return "post-response"
	default:
		return "unknown"
	}
}

// phases returns all phases in execution order.
func phases() []Phase {
	return []Phase{Register, PreParse, PostParse, PreRequest, PostResponse}
}

// Context carries mutable state through the handler chain. Each phase
// populates additional fields; earlier-phase fields remain available in
// later phases so that handlers can correlate raw input with structured
// parameters.
type Context struct {
	// Args is the raw argv slice (available from PreParse onward).
	// PreParse handlers may rewrite this in place.
	Args []string

	// Command identifies the resolved command. RunPreParse fills it with
	// Cobra's raw CommandPath() (e.g. "dws chat message send-by-bot") so
	// PreParse handlers can key per-command tables; the PostParse pipeline
	// fills it with the resolved product.tool canonical path. The two phases
	// use independent Context instances, so the differing forms never mix.
	Command string

	// Params holds structured key→value parameters after Cobra
	// parsing (available from PostParse onward). Handlers may
	// mutate values or add/remove keys.
	Params map[string]any

	// Schema is the JSON Schema for the resolved tool's input
	// (available from PostParse onward). Handlers must treat this
	// as read-only.
	Schema map[string]any

	// Payload is the merged, validated payload ready to be sent
	// over the wire (available from PreRequest onward).
	Payload map[string]any

	// Response is the JSON-RPC result returned by the server
	// (available from PostResponse onward). Handlers may mutate
	// the response before it is written to stdout.
	Response map[string]any

	// FlagSpecs provides the list of known flag names for the
	// current tool, derived from the input schema. PreParse
	// handlers use this to match against raw argv tokens.
	FlagSpecs []FlagInfo

	// ProtectedFlags carries reviewed semantic guard decisions across the
	// complete PreParse chain. Keys are morphed flag names. Sticky and fuzzy
	// handlers must not reinterpret a name classified as blocked or ambiguous
	// by the semantic alias table.
	ProtectedFlags map[string]FlagProtection

	// Corrections records every correction applied by handlers,
	// enabling downstream logging and debugging.
	Corrections []Correction
}

// FlagProtection identifies why an emitted flag name must not be automatically
// rewritten.
type FlagProtection string

const (
	FlagProtectionBlocked   FlagProtection = "blocked"
	FlagProtectionAmbiguous FlagProtection = "ambiguous"
)

// ProtectFlag records a reviewed no-touch decision for the remainder of the
// current pipeline context.
func (c *Context) ProtectFlag(morphed string, protection FlagProtection) {
	if c == nil || morphed == "" {
		return
	}
	if c.ProtectedFlags == nil {
		c.ProtectedFlags = make(map[string]FlagProtection)
	}
	c.ProtectedFlags[morphed] = protection
}

// IsFlagProtected reports whether a morphed flag name is guarded from further
// automatic interpretation.
func (c *Context) IsFlagProtected(morphed string) bool {
	if c == nil {
		return false
	}
	_, ok := c.ProtectedFlags[morphed]
	return ok
}

// FlagConflictError is returned when multiple distinct spellings that reduce
// to one scalar canonical flag are present in the same argv. Rejecting the
// command makes the outcome independent of argument order.
type FlagConflictError struct {
	Command   string
	Canonical string
	Spellings []string
}

func (e *FlagConflictError) Error() string {
	spellings := append([]string(nil), e.Spellings...)
	sort.Strings(spellings)
	for i := range spellings {
		spellings[i] = "--" + strings.TrimPrefix(spellings[i], "--")
	}
	return fmt.Sprintf("conflicting parameter spellings for --%s on %q: %s; pass exactly one spelling", e.Canonical, e.Command, strings.Join(spellings, ", "))
}

// BoolValueConflictError is returned when one canonical boolean flag receives
// both true and false in the same argv. Rejecting contradictory values keeps
// the outcome independent of argument order while allowing repeated identical
// spellings to retain Cobra's native behaviour.
type BoolValueConflictError struct {
	Command string
	Flag    string
	Values  []string
}

func (e *BoolValueConflictError) Error() string {
	values := append([]string(nil), e.Values...)
	sort.Strings(values)
	return fmt.Sprintf("conflicting boolean values for --%s on %q: %s; pass exactly one value", strings.TrimPrefix(e.Flag, "--"), e.Command, strings.Join(values, ", "))
}

// FlagInfo describes a single CLI flag derived from a tool's input
// schema. PreParse handlers use this to recognise valid flag names
// when performing fuzzy matching or alias resolution.
type FlagInfo struct {
	// Name is the canonical kebab-case flag name (e.g. "user-id").
	Name string

	// Shorthand is the optional single-character pflag shorthand (e.g. "y"
	// for --yes). PreParse uses exact shorthand tokens when normalising
	// explicit boolean values; shorthand clusters retain native pflag syntax.
	Shorthand string

	// PropertyName is the original schema property key (e.g. "userId").
	PropertyName string

	// Type is the JSON Schema / pflag type ("string", "integer",
	// "bool", "stringSlice", "duration", etc.).
	Type string

	// Format carries the JSON Schema "format" hint when present —
	// e.g. "date", "date-time", "duration", "email", "uri", "ipv4".
	// PreParse handlers use this to decide whether a suffix in a
	// glued token (e.g. "--starttime1") looks like a plausible value.
	Format string

	// Enum carries the JSON Schema "enum" string values when present.
	// PreParse handlers use this for sticky-split validation: a glued
	// suffix is accepted only if it matches one of the enum entries.
	Enum []string
}

// Correction records a single input correction applied by a handler.
type Correction struct {
	// Handler is the name of the handler that applied the correction.
	Handler string

	// Phase is the pipeline phase in which the correction occurred.
	Phase Phase

	// Field identifies the affected flag or parameter name.
	Field string

	// Original is the value before correction.
	Original string

	// Corrected is the value after correction.
	Corrected string

	// Kind classifies the correction (e.g. "alias", "sticky", "case").
	Kind string
}

// AddCorrection appends a correction record to the context.
func (c *Context) AddCorrection(handler string, phase Phase, field, original, corrected, kind string) {
	c.Corrections = append(c.Corrections, Correction{
		Handler:   handler,
		Phase:     phase,
		Field:     field,
		Original:  original,
		Corrected: corrected,
		Kind:      kind,
	})
}