package contracts

import (
	"context"
	"encoding/json"
	"fmt"

	"gitea.maximumdirect.net/eric/audita/internal/core/chunking"
	"gitea.maximumdirect.net/eric/audita/internal/core/config"
	"gitea.maximumdirect.net/eric/audita/internal/core/schema"
	"gitea.maximumdirect.net/eric/audita/internal/framework/proposals"
)

// StructuredLLMClient provides provider-agnostic structured completion.
type StructuredLLMClient interface {
	CompleteStructured(ctx context.Context, req StructuredCompletionRequest) (StructuredCompletionResponse, error)
}

// TranscriptModule is the minimal contract for framework-integrated modules.
type TranscriptModule interface {
	Key() string
	ReplacementPolicy() proposals.ReplacementPolicy
	Validators() []Validator
	Propose(ctx context.Context, req ProposalRequest) ([]proposals.CorrectionProposal, error)
}

// Validator evaluates candidate proposals and returns one decision per proposal index.
type Validator interface {
	Name() string
	Validate(ctx context.Context, req ValidationRequest) ([]ValidationDecision, error)
}

// StructuredCompletionRequest is a transport-neutral structured completion request.
type StructuredCompletionRequest struct {
	StageName      string          `json:"stage_name"`
	Messages       []LLMMessage    `json:"messages"`
	ResponseSchema json.RawMessage `json:"response_schema,omitempty"`
}

// StructuredCompletionResponse is a transport-neutral structured completion response payload.
type StructuredCompletionResponse struct {
	Content json.RawMessage `json:"content"`
}

// LLMMessage is a minimal chat message shape for LLM prompts.
type LLMMessage struct {
	Role    string `json:"role"`
	Content string `json:"content"`
}

// ModuleRunSpec identifies one resolved module instance in a pipeline.
type ModuleRunSpec struct {
	ModuleKey         string                      `json:"module_key"`
	InstanceName      string                      `json:"instance_name"`
	ReplacementPolicy proposals.ReplacementPolicy `json:"replacement_policy"`
}

// SectionMetadata captures chunk-level metadata without embedding full segment payloads.
type SectionMetadata struct {
	Index           int `json:"section_index"`
	StartSegmentID  int `json:"start_segment_id"`
	EndSegmentID    int `json:"end_segment_id"`
	EstimatedTokens int `json:"estimated_tokens"`
}

// SectionMetadataFromSection converts a chunking section into framework metadata.
func SectionMetadataFromSection(section chunking.Section) SectionMetadata {
	return SectionMetadata{
		Index:           section.Index,
		StartSegmentID:  section.StartSegmentID,
		EndSegmentID:    section.EndSegmentID,
		EstimatedTokens: section.EstimatedTokens,
	}
}

// ExecutionContext carries shared execution state for proposal generation and validation.
type ExecutionContext struct {
	Config            *config.Config     `json:"-"`
	WorkingTranscript *schema.Transcript `json:"-"`
	Glossary          *schema.Glossary   `json:"-"`
	Section           *SectionMetadata   `json:"section,omitempty"`
	DiagnosticsDir    string             `json:"diagnostics_dir,omitempty"`
}

// ProposalRequest is the input to module proposal generation.
type ProposalRequest struct {
	ExecutionContext
	RunSpec   ModuleRunSpec       `json:"run_spec"`
	LLMClient StructuredLLMClient `json:"-"`
}

// ValidationRequest is the input to validator execution.
type ValidationRequest struct {
	ExecutionContext
	RunSpec            ModuleRunSpec                          `json:"run_spec"`
	CandidateProposals []proposals.EnrichedCorrectionProposal `json:"candidate_proposals"`
}

// ValidationDecision is one validator decision for one proposal index.
type ValidationDecision struct {
	ProposalIndex int      `json:"proposal_index"`
	Approved      bool     `json:"approved"`
	Confidence    *float64 `json:"confidence,omitempty"`
	Reason        string   `json:"reason,omitempty"`
}

// ResolveModuleRunSpecs deterministically resolves instance names from logical keys.
// Repeated keys are suffixed with _<n> (1-based), while singleton keys keep their raw key.
func ResolveModuleRunSpecs(moduleKeys []string) ([]ModuleRunSpec, error) {
	totals := make(map[string]int, len(moduleKeys))
	for i, key := range moduleKeys {
		if key == "" {
			return nil, fmt.Errorf("module key at index %d must not be empty", i)
		}
		totals[key]++
	}

	seen := make(map[string]int, len(totals))
	specs := make([]ModuleRunSpec, len(moduleKeys))
	for i, key := range moduleKeys {
		seen[key]++

		name := key
		if totals[key] > 1 {
			name = fmt.Sprintf("%s_%d", key, seen[key])
		}

		specs[i] = ModuleRunSpec{
			ModuleKey:    key,
			InstanceName: name,
		}
	}

	return specs, nil
}