package inventory

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

	"github.com/jackc/pgx/v5"
)

// A Plan is what a merge produces (novox/hq ADR 0162): the modules it changed and everything
// standing on them, sorted into tiers, each module's state, and the tier the plan is at. Kept in
// the store so a controller replaced mid-plan resumes it, and so `status` can say what a merge
// still waits for.
type Plan struct {
	ID         string                 `json:"id"`
	Repository string                 `json:"repository"`
	Commit     string                 `json:"commit"`
	Created    time.Time              `json:"created"`
	Updated    time.Time              `json:"updated"`
	State      string                 `json:"state"`
	Tier       int                    `json:"tier"`
	Tiers      [][]string             `json:"tiers"`
	Modules    map[string]*PlanModule `json:"modules"`
	Note       string                 `json:"note,omitempty"`
}

// PlanModule is one module's state within a plan.
type PlanModule struct {
	// State: asked, built, failed; empty for a module whose tier has not been asked yet.
	State   string     `json:"state,omitempty"`
	AskedAt *time.Time `json:"asked_at,omitempty"`
	BuiltAt *time.Time `json:"built_at,omitempty"`
	// SentAt is when the plan sent the machines running this module its new build, because a
	// later tier is built by it (ADR 0163's gate): the reports that open the gate are the ones
	// after this.
	SentAt *time.Time `json:"sent_at,omitempty"`
	Commit string     `json:"commit,omitempty"`
	Why    string     `json:"why,omitempty"`
}

// The states a plan passes through.
const (
	PlanBuilding = "building"
	PlanRolling  = "rolling"
	PlanDone     = "done"
	PlanFailed   = "failed"
)

// Open says whether the plan is still being worked.
func (p Plan) Open() bool { return p.State == PlanBuilding || p.State == PlanRolling }

// SavePlan writes a plan, new or changed, whole: the plan is small and read as one thing.
func (i *Inventory) SavePlan(ctx context.Context, p Plan) error {
	tiers, err := json.Marshal(p.Tiers)
	if err != nil {
		return err
	}
	modules, err := json.Marshal(p.Modules)
	if err != nil {
		return err
	}
	_, err = i.store.Pool().Exec(ctx,
		`insert into release_plan (id, repository, commit_hash, created, updated, state, tier, tiers, modules, note)
		 values ($1, $2, $3, $4, now(), $5, $6, $7, $8, $9)
		 on conflict (id) do update set updated = now(), state = excluded.state, tier = excluded.tier,
		        tiers = excluded.tiers, modules = excluded.modules, note = excluded.note`,
		p.ID, p.Repository, p.Commit, p.Created, p.State, p.Tier, tiers, modules, p.Note)
	return err
}

// OpenPlans is every plan still being worked, oldest first.
func (i *Inventory) OpenPlans(ctx context.Context) ([]Plan, error) {
	return i.plans(ctx, `where state in ('building', 'rolling') order by created`)
}

// RecentPlans is the last few plans, newest first, open or not — what the overview shows.
func (i *Inventory) RecentPlans(ctx context.Context, limit int) ([]Plan, error) {
	return i.plans(ctx, fmt.Sprintf(`order by created desc limit %d`, limit))
}

// PlanByID is one plan.
func (i *Inventory) PlanByID(ctx context.Context, id string) (Plan, error) {
	plans, err := i.plans(ctx, `where id = '`+id+`'`)
	if err != nil {
		return Plan{}, err
	}
	if len(plans) == 0 {
		return Plan{}, fmt.Errorf("no plan %s", id)
	}
	return plans[0], nil
}

func (i *Inventory) plans(ctx context.Context, tail string) ([]Plan, error) {
	rows, err := i.store.Pool().Query(ctx,
		`select id, repository, commit_hash, created, updated, state, tier, tiers, modules, note
		   from release_plan `+tail)
	if err != nil {
		return nil, err
	}
	defer rows.Close()
	var out []Plan
	for rows.Next() {
		var p Plan
		var tiers, modules []byte
		if err := rows.Scan(&p.ID, &p.Repository, &p.Commit, &p.Created, &p.Updated, &p.State,
			&p.Tier, &tiers, &modules, &p.Note); err != nil {
			return nil, err
		}
		if err := json.Unmarshal(tiers, &p.Tiers); err != nil {
			return nil, err
		}
		if err := json.Unmarshal(modules, &p.Modules); err != nil {
			return nil, err
		}
		if p.Modules == nil {
			p.Modules = map[string]*PlanModule{}
		}
		out = append(out, p)
	}
	if errors.Is(rows.Err(), pgx.ErrNoRows) {
		return nil, nil
	}
	return out, rows.Err()
}